Search for: fuzzy-logic
0.014 seconds
Total 260 records

    Robust fuzzy multimodel control using variable structure system

    , Article 2004 IEEE Conference on Cybernetics and Intelligent Systems, 1 December 2004 through 3 December 2004 ; 2004 , Pages 497-502 ; 0780386442 (ISBN); 9780780386440 (ISBN) Sadati, N ; Talasaz, A ; Sharif University of Technology
    The robust fuzzy multimodel control as a potential tool to control the complex systems is presented in this paper. The main idea in multimodel controllers is to identify the best model of system at any instant and apply the appropriate control input to it. Classical multimodel controller works based on switching and tuning, while fuzzy logic is used in construction of fuzzy multimodel controller. The basic control signal for each model is calculated using the sliding mode control and the final control input is inferred as the weighted average of the local control inputs. A new algorithm is proposed in order to use the fuzzy multimodel control for time variant linear systems. To show the... 

    An adaptive fuzzy logic based handoff algorithm for interworking between WLANs and mobile networks

    , Article 13th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2002, Lisboa, 15 September 2002 through 18 September 2002 ; Volume 5 , 2002 , Pages 2446-2451 ; 0780375890 (ISBN); 9780780375895 (ISBN) Majlesi, A ; Khalaj, B. H ; Sharif University of Technology
    In this paper, the goal is to propose an optimal handoff algorithm for hybrid networks (HNs), which are constructed by interworking between wireless LANs (WLANs) and mobile networks. The proposed algorithm is an adaptive fuzzy logic based algorithm that can adapt itself with the dynamic conditions in HNs. It uses mobile terminal speed estimation and traffic in the WLAN as additional input parameters. This algorithm is designed to meet special requirements of HNs. The simulation results show that it has much better performance than conventional algorithms. ©2002 IEEE  

    Modeling of melatonin behavior in major depression: A fuzzy logic modeling

    , Article Applied Mechanics and Materials ; Volume 367 , June , 2013 , Pages 317-321 ; 16609336 (ISSN) ; 9783037857885 (ISBN) Azizi, A ; Osgouie, K. G ; Rashidnejhad, S ; Cheragh, M ; Sharif University of Technology
    According to the world health organization, major depressive disorder (MDD) is considered as the fourth main cause of death and premature weakness in the whole world. Abnormality in the hormones and neurotransmitters level is the one of the main factors which may result in this disorder. In this article melatonin is chosen among these hormones, which is the most implicated to control sleep and depression. Because the measurement of melatonin is crucial important, the fuzzy logic approach as the mathematical method is utilized to making melatonin behavior model. In this paper, two effective factors on melatonin are modeled by fuzzy logic. This model is only a part of our project which is... 

    Modeling of Major Depression by Using Computational Intelligence

    , M.Sc. Thesis Sharif University of Technology Darvish, Setareh (Author) ; Seifipour, Navid (Supervisor)
    Mental disorders are very common nowadays and affect a person’s everyday life, as well as the lives of other people around him/her. According to the World Health Organization, major depressive disorder (MDD) is considered as the fourth main cause of death and premature weakness in the whole world. Information Technology (IT) could be used to diagnose the people who are affected by the mental disorders as well as reduce their effects. As clinical decision making inherently requires reasoning under uncertainty, fuzzy logic is a suitable technique for dealing with this partial evidence. The fuzzy logic is the science of reasoning; thinking and inference that recognizes and uses the real world... 

    Fuzzy real-time optimization of the Tennessee Eastman challenge process

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 30, Issue 3 , 2011 , Pages 31-43 ; 10219986 (ISSN) Golshan, M ; Bozorgmehry Boozarjomehry, R ; Sahlodin, A. M ; Pishvaie, M. R ; Sharif University of Technology
    A Real-Time Optimization (RTO) strategy incorporating the fuzzy sets theory is developed, where the problem constraints obtained from process considerations are treated in fuzzy environment. Furthermore, the objective function is penalized by a fuzzified form of the key process constraints. To enable using conventional optimization techniques, the resulting fuzzy optimization problem is then reformulated into a crisp programming problem. The crisp programming problem is solved using both Sequential Quadratic Programming (SQP) and Heuristic Random Optimization (HRO) techniques for comparison purposes. The proposed fuzzy RTO strategy is demonstrated via the Tennessee Eastman benchmark process,... 

    Fault diagnosis in a yeast fermentation bioreactor by genetic fuzzy system

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 29, Issue 3 , 2010 , Pages 61-72 ; 10219986 (ISSN) Tayyebi, S ; Shahrokhi, M ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology
    In this paper, the fuzzy system has been used for fault detection and diagnosis of a yeast fermentation bioreactor based on measurements corrupted by noise. In one case, parameters of membership functions are selected in a conventional manner. In another case, using certainty factors between normal and faulty conditions the optimal values of these parameters have been obtained through the genetic algorithm. These two cases are compared based on their performances in fault diagnosis of a yeast fermentation bioreactor for three different conditions. The simulation results indicate that the fuzzy-genetic system is superior in multiple fault detection for the conditions where the minimum and... 

    Iterative univariate optimization of nonlinear trusses with fuzzy strain constraints

    , Article Engineering Optimization ; Volume 36, Issue 6 , 2004 , Pages 677-690 ; 0305215X (ISSN) Joghataie, A ; Allahverdipur, N. H ; Sharif University of Technology
    A univariate iterative method for the optimization of nonlinear trusses with fuzzy constraints is proposed. The method is based on the control of elemental strains rather than stresses and hence it is called the desirable strain design criteria method. The objective of the fuzzy optimization is to find a design so that the weight or volume of the truss as well as all of the constraints on the elemental strains and joint deflections are desirable and satisfactory according to the fuzzy designer expressions. Such expressions are made in the form of fuzzy membership functions. Two illustrative examples, a 3- and a 10-bar truss, are optimized by the proposed method, where it is shown that in... 

    A robust fuzzy sliding mode control for uncertain dynamic systems

    , Article 2004 IEEE International Conference on Systems, Man and Cybernetics, SMC 2004, The Hague, 10 October 2004 through 13 October 2004 ; Volume 3 , 2004 , Pages 2225-2230 ; 1062922X (ISSN) Sadati, N ; Talasaz, A ; Sharif University of Technology
    This paper focuses on the sliding mode control which incorporates a fuzzy tuning technique. In this scheme, first, a control input based on classical sliding mode control is designed. Then, for performance enhancement and chattering elimination, an additional fuzzy control term is used together with the control signal. Furthermore the Lyapunov stability method is used to prove the asymptotic convergence of control strategies. To illustrate the usefulness of the proposed approach, classical and fuzzy sliding mode control are both applied to a flexible transmission system. The results verify the validity of the proposed control scheme. © 2004 IEEE  

    Robustness of A biped robot controller developed by human expertise extraction against changes in terrain

    , Article Proceedings of the IASTED International Conference on Artificial Intelligence and Applications (as part of the 22nd IASTED International Multi-Conference on Applied Informatics, Innsbruck, 16 February 2004 through 18 February 2004 ; 2004 , Pages 68-73 ; 088986375X (ISBN); 9780889863750 (ISBN) Tabrizi, S. S ; Bagheri, S ; IASTED ; Sharif University of Technology
    Controlling dynamic biped robots is a complex challenge. Almost all researches in this field assume that the internal structure and dynamics of the robot is known to the controller. But in real-world problems we don't have exact model of the robot or this model is very complicated and is not useful in real-time control. As a matter of fact, we use many devices without any knowledge about their internal structure or analytical models. Some researchers used learning algorithms to control bipeds, but their performance is not comparable to human's learning. Fuzzy controllers can control the bipeds with lower cost, but they need sufficient rules. In the previous works we proposed a linguistic... 

    The select of a permanent magnet brushed DC motor with optimal controller for providing propellant of @home mobile robot

    , Article 2010 IEEE International Conference on Mechatronics and Automation, ICMA 2010, 4 August 2010 through 7 August 2010 ; August , 2010 , Pages 1137-1141 ; 9781424451418 (ISBN) Zareh, S. H ; Khosroshahi, M ; Abbasi, M ; Ghaemi Osgouie, K ; Sharif University of Technology
    This paper first will describe @Home Mobile Robot and DC motors. In continuous, is designed a Direct current (DC) motor for special task due to specific speed diagram for considered robot. This robot wants to work in intermittent operation condition. Finally is done a speed control on a selected permanent magnet brushed DC motor using of Linear-Quadratic-Regulator (LQR), Linear-Quadratic-Gaussian (LQG) and Fuzzy logic controllers  

    Power system transient stability improvement using fuzzy controlled STATCOM

    , Article 2006 International Conference on Power System Technology, POWERCON2006, Chongqing, 22 October 2006 through 26 October 2006 ; 2006 ; 1424401119 (ISBN); 9781424401116 (ISBN) Zolghadri, M. R ; Ghafori, A ; Ehsan, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2006
    In this paper a fuzzy logic based controller for STATCOM is used to improve power system transient stability. As opposed to the modern control theory, fuzzy logic design is not based on the mathematical model of the process. The controller designed using fuzzy logic implements human reasoning that can be programmed into fuzzy logic language (membership functions, rules and the rule interpretation). The nonlinear fuzzy controller is proposed to supply a supplementary control signal to STATCOM to increase the critical clearing time and overcome the uncertainties existing in the power systems. Proposed method is implemented in a single machine infinite bus system and the results are compared... 

    Airport Capacity Determination by Fuzzy Logic

    , M.Sc. Thesis Sharif University of Technology Tanha, Mahdieh (Author) ; Malaek, Mohammad Bagher (Supervisor)
    An automatic air traffic controller system is designed in this research. The major goal is to aid the human controller in decision making at real air traffic control situations. The air traffic system is modeled by queuing theory. Since respond rapidity is very important in air traffic control, so the fuzzy logic is utilized to construct a rule-base. This rule-base determines optimum policies while considering the operational matters, minimum separation distance requirements, air traffic controller techniques, and work-load. This project is an initial design for air traffic automation system which considers scheduling optimality as well as delay reduction. The case study is done on Denver... 

    Implementation of Network User’s Fuzzy Perceived Travel Time in Stochastic Traffic Assignment

    , M.Sc. Thesis Sharif University of Technology Shabanpour Anbarani, Ramin (Author) ; Shafahi, Yusof (Supervisor)
    Traffic assignment is one of the key steps in transportation planning. In this stage, link flows are obtained based on estimated O-D demand in previous steps. The first Wardrop rule is the base for all of proposed traffic assignment models. In these models, number of assumptions has been relaxed to make it more realistic. Stochastic traffic assignment and fuzzy rule are two different approaches to capture the realistic picture of route choice behavior of travelers. In this thesis, we utilize the stochastic distributions to model the fuzzy perception of travelers from link experienced travel time. With using utility theory, fuzzy utility estimation method is proposed as an approach to... 

    Energy Optimization in Visbreaker Furnace

    , M.Sc. Thesis Sharif University of Technology Goshayeshi, Babak (Author) ; Pishvaie, Mahmoud Reza (Supervisor) ; Farhadi, Fathollah (Supervisor)
    In this project Visbreaker furnace was modeled and optimized. For this goal, Lobo & Evans method and refinery data was used. Effect of parameters such as, excess air, stack height, decoking period, burn out and fuel heat value were investigated. Among optimization method, genetic algorithm and MITA (Musical Instrument Tempering Algorithm) were used to minimizing cost function of furnace. Also based on Zone method, profiles of properties of process fluid were obtained. Finally fuzzy logic was used for furnace behavior identification  

    , M.Sc. Thesis Sharif University of Technology (Author) ; Taghikhani, Vahid (Supervisor) ; Bozorg Mehri, Ramin (Supervisor) ; Ghotbi, Siroos (Supervisor)
    Gas hydrate is a nonstoichiometric structure that has been produced from water and gas in appropriate thermal and pressure conditions. There has been a long time that scientists work on predicting hydrate production condition. Predicting the hydrate behavior for pure substances is easier than mixtures; because there are some behaviors of mixtures that we do not know their reasons yet. In this thesis, there has been tried to give a model to describe hydrate reactions to temperature and pressure changes besides predicting the hydrate type and the cage occupancy. Since the hydrate behavior is nonstoichiometric, it is useful to know the cage occupancy to predict the amount of hydrate... 

    Modeling of Gas Hydrate Formation in Presence of Inhibitors Using the Fuzzy Logic

    , M.Sc. Thesis Sharif University of Technology Falahati, Mojtaba (Author) ; Taghikhani, Vahid (Supervisor) ; Ghotbi, Cyrus (Supervisor)
    Nowadays oil and gas industry has taken the pulse of world energy. Different countries of the world are trying more and more to explore and produce this black gold. To do so these countries has gained many experiences and even gone to seas and oceans to find oil and gas. In the process, they has faced with a new phenomenon called gas hydrate. The phenomenon which was unknown and destructive at first after excessive research, today is even called as the future energy source of the world. But what we discussed in this study is hydrate as a problem in oil and gas industry. Gas hydrates are formed in favorable temperature and pressure condition (low temperature and high pressure) in the... 

    Design of the LQR controller and observer with fuzzy logic GA and GA-PSO algorithm for triple an inverted pendulum and cart system

    , Article International Conference on Advanced Mechatronic Systems, ICAMechS ; 25 September , 2014 , Pages 295-300 ; ISSN: 23250682 ; ISBN: 9781479963812 Molazadeh, V. R ; Banazadeh, A ; Shafieenejad, I ; Sharif University of Technology
    In this paper, designing of the LQR controller and observer with intelligent tools for the triple inverted pendulum is investigated. Intelligent tools are considered as GA and GA-PSO optimization algorithms and fuzzy logic to qualify achieving LQR gains. The pendulum is swung up from the vertical position to the unstable position. The rules for the controlled swing up are heuristically achieved such that each swing results are controlled. The inverted pendulum and cart system are modeled and constructed their equation based on energy method. Also, the performances of the proposed fuzzy logic controller, GA and GA-PSO tuning LQR gains are investigated and compared. Simulation results show... 

    Design of fuzzy logic control system incorporating human expert knowledge for combine harvester

    , Article Expert Systems with Applications ; Volume 37, Issue 10 , 2010 , Pages 7080-7085 ; 09574174 (ISSN) Omid, M ; Lashgari, M ; Mobli, H ; Alimardani, R ; Mohtasebi, S ; Hesamifard, R ; Sharif University of Technology
    Many factors affect the yield loss in wheat harvesting with a grain combine harvester. Grain harvesting is a non-linear process, is of considerable complexity, and there is no mathematical model to describe the behavior of this complex system. In this paper, a fuzzy logic controller (FLC) incorporating human expert knowledge is designed for automatic adjustment and control of the harvester to achieve minimal grain losses especially at the position of straw walker and upper sieve. The FLC automatically adjusts cylinder speed, concave clearance, fan speed and forward speed of the combine based on the measured losses at straw walker and sieve sections. The designed FLC expert system consists... 

    Feed-forward modelling and fuzzy logic based control strategy for powertrain efficiency improvement in a parallel hybrid electric vehicle

    , Article Mathematical and Computer Modelling of Dynamical Systems ; Volume 15, Issue 2 , 2009 , Pages 191-207 ; 13873954 (ISSN) Amiri, M ; Esfahanian, V ; Hairi Yazdi, M. R ; Esfahanian, M ; Fazeli, A. M ; Nabi, A ; Sharif University of Technology
    With the stricter limitations on both fuel consumption and air pollution, the advantages of a hybrid electric vehicle are becoming more evident than ever. In the present study, an energy management system for a hybrid electric vehicle is developed. Because the plant under consideration is nonlinear, multi-domain, time-varying, has multiple uncertainties and, in addition, the designed control strategy must be able to obey the driver's commands and achieve the par-internship for a new generation of vehicle regulations, the fuzzy logic approach is chosen. A feed-forward hybrid vehicle simulation model is used to demonstrate the validity and the convenience of the current approach and its... 

    A fuzzy-AHP-based approach to select software architecture based on quality attributes (FASSA)

    , Article Knowledge and Information Systems ; Volume 62, Issue 12 , 13 August , 2020 , Pages 4569-4597 Moaven, S ; Habibi, J ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2020
    The software system design phase has recently received increasing attention due to continuous growth in both the size and complexity of software systems. As a key concept of this phase, software architecture plays an important role in the software extension cycle to the extent that the success of a software project is often determined by the degree of its design efficiency. In addition, software architecture evaluation is a fundamental step toward its subsequent validation. This paper is an attempt to propose an innovative method, based on fuzzy logic, to evaluate software architecture that addresses the inherent problems of existing methods found in the literature. The method can be used...