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Modified artificial bee colony algorithm based on fuzzy multi-objective technique for optimal power flow problem
, Article Electric Power Systems Research ; Volume 95 , 2013 , Pages 206-213 ; 03787796 (ISSN) ; Hosseinian, S. H ; Ghazanfari, A ; Sharif University of Technology
2013
Abstract
This paper presents a fuzzy based modified artificial bee colony (MABC) algorithm to solve discrete optimal power flow (OPF) problem that has both discrete and continuous variables considering valve point effects. The OPF problem is formulated as a multi-objective mixed-integer nonlinear problem, where optimal settings of the OPF control variables for simultaneous minimization of total fuel cost of thermal units, total emission, total real power losses, and voltage deviation are obtained. The proposed approach is applied to the OPF problem on IEEE 30-bus and IEEE 118-bus test systems. The performance and operation of the proposed approach is compared with the conventional methods. The...
Improvement of Control of Hybrid AC-DC Microgrid in Islanded Mode
, Ph.D. Dissertation Sharif University of Technology ; Mokhtari, Hossein (Supervisor)
Abstract
A microgrid is a collection of loads, sources, and power storage units that operates as a single controllable system and can operate in grid-connected or islanded mode. From the generating side, renewable energy resources such as photovoltaic system, fuel cell and power storage units are inherently DC. From the load side, electronic loads such as computers, data centers and most of the variable speed motor drives require a DC supply. Therefore, DC Microgrids have gained widespread attention in recent years. On the other hand, since existing distribution systems are mostly AC, a hybrid microgrid is more likely. The hybrid microgrid is composed of two AC and DC subgrids interlinked by power...
Non-Rigid Medical Image Registration Based on Information Theory
, M.Sc. Thesis Sharif University of Technology ; Fatemizadeh, Emadoddin (Supervisor)
Abstract
The registration of images is a fundamental task in numerous applications in medical image processing. The importance of medical image registraiton due to the imaging systems development in last decades is obvious to every one. Especially the wide employment and different capabilities of these systems has caused more attention to this field of image processing. Th e application of medical image registraiton is extended from clinical diagnosis and treatment evaluation, to image guided surgery. The dimension of images as well as modalities of imaging and imaging subjectshas made a wide variety of problems in this branch of image processing. Registration, briefly speaking, is a geometrical...
Dependence of Surface Tension on Temperature and Density in the Interface of Liquid & Vapour
, M.Sc. Thesis Sharif University of Technology ; Parsafar, GholamAbbas (Supervisor)
Abstract
In this thesis dependency of surface tension ( ) on temperature (T ) and density (?), for spherical and nearly spherical fluids like argon has been investigated, using an effective Lennard – Jones (12,6) potential along with a new model according to which half of surface molecules are assumed to be in the liquid phase and the other half in the vapor phase, far from the critical point. The obtained result may be expressed as ? ? ? ( The 2 2= +C D C and D parameters are independent of T and ?). Such an investigation has also been done for many fluids, but by using the extended Lennard – Jones (12, 6, 3) function as the effective pair...
A decentralized control method for a low-voltage dc microgrid
, Article IEEE Transactions on Energy Conversion ; Vol. 29, issue. 4 , Dec , 2014 , p. 793-801 ; 08858969 ; Ashourloo, M ; Mokhtari, H ; Sharif University of Technology
2014
Abstract
DC microgrids (DC-MGs) are becoming popular as an effective means to integrate various renewable energy resources. Conventionally, the droop control is adopted as a decentralized control strategy for proper power sharing without using any communication link. However, the conventional droop control often deteriorates due to the effects of unequal line resistances. In this paper, a control strategy is proposed for a DC-MG to achieve perfect power sharing considering the effects of line resistances. The DC-MG under study consists of a photovoltaic system, two energy storage systems, a grid-connected converter system, and dc loads. The control strategy of the converters is addressed under...
An adaptive droop control method for low voltage DC microgrids
, Article PEDSTC 2014 - 5th Annual International Power Electronics, Drive Systems and Technologies Conference ; December , 2014 , p. 84-89 ; Ashourloo, M ; Mokhtari, H ; Sharif University of technology
2014
Abstract
DC microgrids (MGs) are becoming popular as effective means to integrate different energy resources. Conventionally, the droop control is adopted as a decentralized control method for power sharing in DC MGs. However, current sharing accuracy or voltage regulation deteriorates due to the effects of line impedances. In this paper, a new adaptive control strategy is proposed for DC MGs. In low load conditions, the output currents of the DGs are far from their maximum acceptable limits. Therefore, current sharing accuracy is not important. As load increases, the output currents of the DGs approach their maximum acceptable limits. Therefore, at high load conditions, accurate current sharing is...
SDxVPN: A software-defined solution for VPN service providers
, Article Proceedings of the NOMS 2016 - 2016 IEEE/IFIP Network Operations and Management Symposium, 25 April 2016 through 29 April 2016 ; 2016 , Pages 180-188 ; 9781509002238 (ISBN) ; Taheri, N ; Khorsandi, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
BGP/MPLS IP VPN and VPLS services are considered to be widely used in IP/MPLS networks for connecting customers' remote sites. However, service providers struggle with many challenges to provide these services. Management complexity, equipment costs, and last but not least, scalability issues emerging as the customers increase in number, are just some of these problems. Software-defined networking (SDN) is an emerging paradigm that can solve aforementioned issues using a logically centralized controller for network devices. In this paper, we propose a SDN-based solution called SDxVPN which considerably lowers the complexity of VPN service definition and management. Our method eliminates...
On the Unit Graph of a Non-commutative Ring
, Article Algebra Colloquium ; Volume 22 , December , 2015 , Pages 817-822 ; 10053867 (ISSN) ; Estaji, E ; Khorsandi, M. R ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
2015
Abstract
Let R be a ring with non-zero identity. The unit graph G(R) of R is a graph with elements of R as its vertices and two distinct vertices a and b are adjacent if and only if a + b is a unit element of R. It was proved that if R is a commutative ring and is a maximal ideal of R such that |R/| = 2, then G(R) is a complete bipartite graph if and only if (R, ) is a local ring. In this paper we generalize this result by showing that if R is a ring (not necessarily commutative), then G(R) is a complete r-partite graph if and only if (R, ) is a local ring and r = |R/| = 2n for some n ∞ N or R is a finite field. Among other results we show that if R is a left Artinian ring, 2 U(R) and the clique...
Introduction of novel dispatching rules for grid scheduling algorithms
, Article International Conference on Computer and Communication Engineering 2008, ICCCE08: Global Links for Human Development, Kuala Lumpur, 13 May 2008 through 15 May 2008 ; 2008 , Pages 1072-1078 ; 9781424416929 (ISBN) ; Mirza Aghatabar, M ; Khorsandi, S ; Sharif University of Technology
2008
Abstract
Grid scheduling problems are dynamic as the jobs and resources in the system vary overtime. The Rulebased scheduling algorithms are a new trend in grid scheduling which are applicable in dynamic grid environments; The arriving jobs waiting for execution is ordered according to a certain rule and they are dispatched for processing according to that order. Grid scheduling algorithms usually involve more than one objective function. In particular, it is not enough to minimize the Maximum completion time (Makespan) objective function without taking into consideration the lateness of the jobs (Tardiness). In this paper two novel dispatching rules are proposed that aims to minimize the maximum...
Are socially-aware trajectory prediction models really socially-aware?
, Article Transportation Research Part C: Emerging Technologies ; Volume 141 , 2022 ; 0968090X (ISSN) ; Bahari, M ; Khorsandi, P ; Saneian, M ; Moosavi Dezfooli, S. M ; Alahi, A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Our transportation field has recently witnessed an arms race of neural network-based trajectory predictors. While these predictors are at the core of many applications such as autonomous navigation or pedestrian flow simulations, their adversarial robustness has not been carefully studied. In this paper, we introduce a socially-attended attack to assess the social understanding of prediction models in terms of collision avoidance. An attack is a small yet carefully-crafted perturbations to fail predictors. Technically, we define collision as a failure mode of the output, and propose hard- and soft-attention mechanisms to guide our attack. Thanks to our attack, we shed light on the...
Automatic droop control for a low voltage DC microgrid
, Article IET Generation, Transmission and Distribution ; Volume 10, Issue 1 , 2016 , Pages 41-47 ; 17518687 (ISSN) ; Ashourloo, M ; Mokhtari, H ; Iravani, R ; Sharif University of Technology
Institution of Engineering and Technology
2016
Abstract
A DC microgrid (DC-MG) provides an effective mean to integrate various sources, energy storage units and loads at a common dc-side. The droop-based, in the context of a decentralised control, has been widely used for the control of the DC-MG. However, the conventional droop control cannot achieve both accurate current sharing and desired voltage regulation. This study proposes a new adaptive control method for DC-MG applications which satisfies both accurate current sharing and acceptable voltage regulation depending on the loading condition. At light load conditions where the output currents of the DG units are well below the maximum limits, the accuracy of the current sharing process is...
Introduction of novel rule based algorithms for scheduling in grid computing systems
, Article 2nd Asia International Conference on Modelling and Simulation, AMS 2008, Kuala Lumpur, 13 May 2008 through 15 May 2008 ; 2008 , Pages 138-143 ; 9780769531366 (ISBN) ; Mirza Aghatabar, M ; Khorsandi, S ; Sharif University of Technology
2008
Abstract
The rule based scheduling algorithms are a new trend in grid scheduling algorithms; the combination of rule based algorithms for resource selection with various dispatching rules for queuing of jobs can improve or deteriorate their performance. Thus, choosing a proper queuing strategy for each algorithm is a prominent issue in scheduling. In this paper, we introduce two new dispatching rules for resource selection and three new dispatching rules for queuing of jobs; we evaluate the performance of various combinations of these new rule based scheduling algorithms and queuing strategies. Also, we use some major combination of rule based scheduling algorithms with some important queuing...
Fully implicit compositional thermal simulator using rigorous multiphase calculations
, Article Scientia Iranica ; Volume 18, Issue 3 C , June , 2011 , Pages 509-517 ; 10263098 (ISSN) ; Bozorgmehry Boozarjomehry, R ; Pishvaie, M. R ; Sharif University of Technology
2011
Abstract
Simulation of the in-situ combustion process is one of the most complex simulations amongst other reservoir flow simulations. Accurate simulation of the process is critical to obtain a successful implementation of the in-situ combustion process. Several factors impact performance of the simulation of this process. First are all the numerical models used for different sub-processes, such as reactions, fluid phase behavior, heat loss to surrounding formations and fluid physical properties. In the previous numerical models of the in-situ combustion process, very simplified models were used for the phase behavior of the fluid. Recent studies show that the fluid phase behavior model has a great...
Using Intelligent Local Thermodynamic Models in Simulation of Thermal EOR Processes
, M.Sc. Thesis Sharif University of Technology ; Bozorgmehri, Ramin (Supervisor) ; Pishvaie, Mahmoud Reza (Supervisor)
Abstract
Fluid property calculation is one of the most time consuming parts of compositional reservoir simulation. Also in thermal reservoir simulations, more iterations and smaller time steps increase number of fluid properties calculations required. Fluid property calculations require multiphase equilibrium calculations which could be very time consuming depending on the level of sophistication of the fluid model used. In this work a simulator with capability to use EoS for fluid property calculations is developed. The simulator uses full implicit finite difference solution scheme. EoS is used as fluid model to increase the accuracy and applicability of simulator for different fluid properties and...
Two phase gas-liquid bubbly flow modeling in vertical mini pipe
, Article 2010 14th International Heat Transfer Conference, IHTC 14, 8 August 2010 through 13 August 2010 ; Volume 3 , 2010 , Pages 947-956 ; 9780791849385 (ISBN) ; Karabi, H ; Khorsandi, S ; Saidi, M. H ; Heat Transfer Division ; Sharif University of Technology
2010
Abstract
Studies on two-phase flow in small scale pipes have become more important, because of the application of mini-scale devices in several engineering fields including, high heat-flux compact heat exchangers, and cooling systems of various types of equipment. In a mini pipe the behavior of two phase flow is not the same as flow in conventional pipes. The difference is caused by different effective forces; for e. g. inside a mini pipe capillary forces are more important in comparison with gravitational forces. This paper is devoted to numerical simulation of gas-liquid two phase flow in a vertical mini pipe. Prediction of bubble shape and the effects of gas and liquid velocities on flow...
Intelligent semi-active vibration control of eleven degrees of freedom suspension system using magnetorheological dampers
, Article Journal of Mechanical Science and Technology ; Volume 26, Issue 2 , 2012 , Pages 323-334 ; 1738494X (ISSN) ; Sarrafan, A ; Khayyat, A. A. A ; Zabihollah, A ; Sharif University of Technology
2012
Abstract
A novel intelligent semi-active control system for an eleven degrees of freedom passenger car's suspension system using magnetorheological (MR) damper with neuro-fuzzy (NF) control strategy to enhance desired suspension performance is proposed. In comparison with earlier studies, an improvement in problem modeling is made. The proposed method consists of two parts: a fuzzy control strategy to establish an efficient controller to improve ride comfort and road handling (RCH) and an inverse mapping model to estimate the force needed for a semi-active damper. The fuzzy logic rules are extracted based on Sugeno inference engine. The inverse mapping model is based on an artificial neural network...
Performance and exhaust emission characteristics of a spark ignition engine operated with gasoline and CNG blend
, Article Proceedings of the Spring Technical Conference of the ASME Internal Combustion Engine Division ; 2012 , Pages 179-187 ; 15296598 (ISSN) ; 9780791844663 (ISBN) ; Hamidi, A. A ; Mozafari, A. A ; Sharif University of Technology
2012
Abstract
Using CNG as an additive for gasoline is a proper choice due to higher octane number of CNG enriched gasoline with respect to that of gasoline. As a result, it is possible to use gasoline with lower octane number in the engine. This would also mean the increase of compression ratio in SI engines resulting in higher performance and lower gasoline consumption. Over the years, the use of simulation codes to model the thermodynamic cycle of an internal combustion engine have developed tools for more efficient engine designs and fuel combustion. In this study, a thermodynamic cycle simulation of a conventional four-stroke spark-ignition engine has been developed. The model is used to study the...
A comparative study of the performance of a SI engine fuelled by natural gas as alternative fuel by thermodynamic simulation
, Article 2009 ASME Internal Combustion Engine Division Fall Technical Conference, ICEF 2009, Lucerne, 27 September 2009 through 30 September 2009 ; 2009 , Pages 49-57 ; 9780791843635 (ISBN) ; Hamidi, A. A ; Mozafari, A. A ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2009
Abstract
With the declining energy resources and increase of pollutant emissions, a great deal of efforts has been focused on the development of alternatives for fossil fuels. One of the promising alternative fuels to gasoline in the internal combustion engine is natural gas [1-5]. The application of natural gas in current internal combustion engines is realistic due to its many benefits. The higher thermal efficiency due to the higher octane value and lower exhaust emissions including CO2 as a result of the lower carbon to hydrogen ratio of the fuel are the two important feature of using CNG as an alternative fuel. It is well known that computer simulation codes are valuable economically as a cost...
Analytical and experimental analyses of nonlinear vibrations in a rotary inverted pendulum
, Article Nonlinear Dynamics ; Volume 107, Issue 3 , 2022 , Pages 1887-1902 ; 0924090X (ISSN) ; Pasharavesh, A ; Khayyat, A. A. A ; Sharif University of Technology
Springer Science and Business Media B.V
2022
Abstract
Gaining insight into possible vibratory responses of dynamical systems around their stable equilibria is an essential step, which must be taken before their design and application. The results of such a study can significantly help prevent instability in closed-loop stabilized systems by avoiding the excitation of the system in the neighborhood of its resonance. This paper investigates nonlinear oscillations of a rotary inverted pendulum (RIP) with a full-state feedback controller. Lagrange’s equations are employed to derive an accurate 2-DoF mathematical model, whose parameter values are extracted by both the measurement and 3D modeling of the real system components. Although the governing...
A suction-controlled ring device to measure the coefficient of lateral soil pressure in unsaturated soils
, Article Geotechnical Testing Journal ; Volume 44, Issue 1 , 2020 ; Garakani, A. A ; Golshani, A ; Mirzaii, A ; Sharif University of Technology
ASTM International
2020
Abstract
A suction-controlled ring device has been developed to continuously measure the coefficient of lateral soil pressure in deformable unsaturated soil samples from the at-rest to the active condition under application of increasing vertical pressure and controlled matric suction. The device incorporates a thin aluminum specimen ring equipped with horizontal strain gages for recording the lateral soil strains. In addition, a sensor recording water volume changes is utilized to continuously monitor the degree of saturation of the soil sample during tests. The matric suction within the soil texture is controlled using the axis translation technique. In order to verify the performance of the ring...