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    Control of car-like (wheeled) multi robots for following and hunting a moving target

    , Article Scientia Iranica ; Volume 18, Issue 4 B , August , 2011 , Pages 950-965 ; 10263098 (ISSN) Sayyaadi, H ; Kouhi, H ; Salarieh, H ; Sharif University of Technology
    2011
    Abstract
    The main purpose of this paper is to design a decentralized controller for some car-like (wheeled) multi robots to follow and hunt a moving target. Considering geometric dimensions, mass and moment of inertia, robots are very similar to actual cars in which the outputs of the controller are steering and driving wheel torques. All robots are equipped with range and bearing sensors along with antenna, to communicate radio wave signals. A Kalman filter is implemented to estimate relative position, state variables of the target and state variables of other robots. The controller is designed to carry out the group maneuver of the system, based on the system dynamics analysis of inertial agents,... 

    An experimental investigation of permeability impairment under dynamic flow conditions due to natural depletion in an Iranian oilfield

    , Article Petroleum Science and Technology ; Volume 31, Issue 3 , 2013 , Pages 250-261 ; 10916466 (ISSN) Khalifeh, M ; Bagherzadeh, H ; Bolouri, H ; Sharif University of Technology
    2013
    Abstract
    Asphaltene deposition is an issue that has received much attention since it has been shown to be the cause of major production problems. It leads to permeability reduction under the processes of natural depletion as well as hydrocarbon gas/CO2 injection. Though a great deal of researches have focused on studying permeability impairment in reservoir rocks, little is known about the asphaltene deposition mechanisms that control the permeability reduction for Iranian reservoirs. In this work, an experimental effort is made to investigate the permeability impairment of core samples of Iranian oil reservoirs. The experiments are performed on both sandstone and carbonate rock types at reservoir... 

    An optimum MMSE post-filter for Adaptive Noise Cancellation in automobile environment

    , Article 2012 11th International Conference on Information Science, Signal Processing and their Applications, ISSPA 2012 ; 2012 , Pages 431-435 ; 9781467303828 (ISBN) Khorram, S ; Sameti, H ; Veisi, H ; Sharif University of Technology
    2012
    Abstract
    Adaptive Noise Cancellation (ANC) is an effective dual-channel technique for background noise reduction. Due to the presence of uncorrelated noise components at the two inputs in vehicular environments, ANC does not provide sufficient background noise reduction. To alleviate this problem, a complementary linear filter is added to ANC structure. Filter coefficients are determined to make the enhanced signal an MMSE estimation of speech signal. Therefore, the ANC structure is modified to a dual-channel Wiener structure. We prove that this structure is identical to the LMS type ANC which is followed by a Wiener post-filter. A new method is proposed for the noise spectrum estimation in the... 

    Speech enhancement based on hidden markov model with discrete cosine transform coefficients using laplace and gaussian distributions

    , Article 2012 11th International Conference on Information Science, Signal Processing and their Applications, ISSPA 2012, 2 July 2012 through 5 July 2012 ; July , 2012 , Pages 304-309 ; 9781467303828 (ISBN) Aroudi, A ; Veisi, H ; Sameti, H ; Sharif University of Technology
    2012
    Abstract
    This paper presents a novel HMM-based speech enhancement framework based on Laplace and Gaussian distributions in DCT domain. We propose analytical procedures for training clean speech and noise models with the aim of Baum's auxiliary function and present two MMSE estimators based on Gaussian-Gaussian (for clean speech and noise respectively) and Laplace-Gaussian combinations in the HMM framework. The performance evaluation is done using SNR and PESQ measures and the results of the proposed techniques are compared with AR-HMM approach. Higher SNR improvement is achieved for the proposed method in the Gaussian-Gaussian case in comparison with AR-HMM and Laplace-Gaussian techniques for both... 

    A new control strategy for a multi-bus MV microgrid under unbalanced conditions

    , Article IEEE Transactions on Power Systems ; Volume 27, Issue 4 , 2012 , Pages 2225-2232 ; 08858950 (ISSN) Hamzeh, M ; Karimi, H ; Mokhtari, H ; Sharif University of Technology
    2012
    Abstract
    This paper proposes a new control strategy for the islanded operation of a multi-bus medium voltage (MV) microgrid. The microgrid consists of several dispatchable electronically-coupled distributed generation (DG) units. Each DG unit supplies a local load which can be unbalanced due to the inclusion of single-phase loads. The proposed control strategy of each DG comprises a proportional resonance (PR) controller with an adjustable resonance frequency, a droop control strategy, and a negative-sequence impedance controller (NSIC). The PR and droop controllers are, respectively, used to regulate the load voltage and share the average power components among the DG units. The NSIC is used to... 

    Modeling of a BDFM-based wind turbine under unbalanced grid voltage dips

    , Article 2011 IEEE Power and Energy Conference at Illinois, PECI 2011 ; 2011 ; 9781424480500 (ISBN) Sotoodeh, P ; Gorgin, H ; Oraee, H ; Sharif University of Technology
    2011
    Abstract
    Brushless Doubly-Fed Machine (BDFM) is a machine which incorporates the robustness of the squirrel cage induction machine while having the speed and power factor control of a synchronous machine. A special kind of rotor called Nested-Loop rotor plays an important part in the BDFM, coupling the two stator fields. In future BDFM will share a large part in wind power market. This paper presents a mathematical model of Brushless Doubly-Fed Machine (BDFM) based on Stator Flux Orientation (SFO) in the positive and negative reference frames under unbalanced grid voltage conditions  

    ON-line learning of a Persian spoken dialogue system using real training data

    , Article 10th International Conference on Information Sciences, Signal Processing and their Applications, ISSPA 2010, 10 May 2010 through 13 May 2010 ; May , 2010 , Pages 133-136 ; 9781424471676 (ISBN) Habibi, M ; Sameti, H ; Setareh, H ; Sharif University of Technology
    2010
    Abstract
    The first spoken dialogue system is developed for the Persian language is introduced. This is a ticket reservation system with Persian ASR and NLU modules. The focus of the paper is on learning the dialogue management module. In this work, real on-line training data are used during the learning process. For on-line learning, the effect of the variations of discount factor (γ) on the learning speed is investigated as the second contribution of the research. The optimal values for γ were found and the variation pattern of the action-value function (Q) in the learning process was obtained. A probabilistic policy for selecting actions is used in this work for the first time instead of greedy... 

    An algebraic gain estimation method to improve the performance of HMM-based speech enhancement systems

    , Article Proceedings - 2010 18th Iranian Conference on Electrical Engineering, ICEE 2010, 11 May 2010 through 13 May 2010 ; 2010 , Pages 336-339 ; 9781424467600 (ISBN) Mariooryad, S ; Sameti, H ; Veisi, H ; Sharif University of Technology
    2010
    Abstract
    An extension to conventional Hidden Markov Model (HMM)-based speech enhancement method is developed. An algebraic method is proposed to estimate gain of speech and noise in order to improve the quality of the estimated speech. Different pronunciations and intonations may affect speech gain. Besides, gain of noise may vary remarkably from one environment to the other one. This may lead in a mismatch between energy contour of trained models and energy contour of noisy speech signal. In this work, speech gain and noise gain are estimated based on an algebraic method simultaneously in order to match gain of noisy speech and noisy model. To carry out this procedure an extension of least square... 

    Seismic assessment of steel frames with the endurance time method

    , Article Journal of Constructional Steel Research ; Volume 66, Issue 6 , 2010 , Pages 780-792 ; 0143974X (ISSN) Riahi, H. T ; Estekanchi, H. E ; Sharif University of Technology
    2010
    Abstract
    In the endurance time (ET) method, structures are subjected to a specially designed intensifying ground acceleration function and their performance is judged based on their response at various excitation levels. A range of equivalent intensities can be covered in a single numerical or experimental simulation, thus significantly reducing the computational demand as compared to full nonlinear response-history analyses. The applied excitation intensity at various times has been correlated with those of the scaled ground motions. Response spectra of seven ground motions on stiff soil were used to produce intensifying acceleration functions that at each time window produce a response spectrum... 

    Classification of gas chromatographic fingerprints of saffron using partial least squares discriminant analysis together with different variable selection methods

    , Article Chemometrics and Intelligent Laboratory Systems ; 2016 , Pages 165-173 ; 01697439 (ISSN) Aliakbarzadeh, G ; Parastar, H ; Sereshti, H ; Sharif University of Technology
    Elsevier  2016
    Abstract
    In the present work, the abilities of five different variable selection methods including recursive partial least squares (rPLS), variable importance in projection (VIP), selectivity ratio (SR), significance multivariate correlation (sMC), and PLS loading weights were evaluated on the supervised classification of gas chromatographic fingerprints of saffron using PLS-discriminant analysis (PLS-DA). In this regard, eighty-three saffron samples analyzed by gas chromatography-flam ionization detector (GC-FID), were used as a case study. The GC-FID chromatograms of saffron samples were baseline corrected and aligned using asymmetric least squares (AsLS) and correlation optimized warping (COW)... 

    Fatty acids profiling of avocado seed and pulp using gas chromatography–mass spectrometry combined with multivariate chemometric techniques

    , Article Journal of the Iranian Chemical Society ; Volume 13, Issue 10 , 2016 , Pages 1905-1913 ; 1735207X (ISSN) Aliakbarzadeh, G ; Sereshti, H ; Parastar, H ; Sharif University of Technology
    Springer Verlag  2016
    Abstract
    In the present study, the profiling of 17 fatty acids (FAs) in avocado seed and pulp was investigated. The fatty acids were extracted with vortex-assisted extraction, methyl esterified and finally preconcentrated by dispersive liquid–liquid microextraction. The preconcentrated fatty acid methyl esters (FAMEs) were analyzed using gas chromatography–mass spectrometry (GC–MS) to obtain qualitative and quantitative information. The GC–MS data were analyzed using multivariate curve resolution-alternating least squares (MCR-ALS) method to overcome general chromatographic problems such as overlapped peaks, background interference and peak shifts. The calibration data were prepared using pure... 

    Optimization of biomass waste gasification combined heat and power system

    , Article EPEC 2010 - IEEE Electrical Power and Energy Conference: "Sustainable Energy for an Intelligent Grid", 25 August 2010 through 27 August 2010, Halifax, NS ; 2010 ; 9781424481880 (ISBN) Fakhimghanbarzadeh, B ; Marzi, H ; Abolghasem, H ; Sharif University of Technology
    2010
    Abstract
    The objective of the research done in this paper was to determine cost of the power and heat system with pressurized fluidized bed gasifier using exergoexonomic appraisal techniques. Exergetic efficiency maximization was approached with use of multi-objective evolutionary optimization methods which were designed such that the costs were minimized in line with the exergoeconomic plans. The results of this method were also compared to methods that employ iterative techniques. Results showed an almost 12.28% improvement in exergetic efficient that the system could reach through utilization of the multi-objective evolutionary algorithm  

    Speaker models reduction for optimized telephony text-prompted speaker verification

    , Article Canadian Conference on Electrical and Computer Engineering, 3 May 2015 through 6 May 2015 ; Volume 2015-June, Issue June , May , 2015 , Pages 1470-1474 ; 08407789 (ISSN) Kalantari, E ; Sameti, H ; Zeinali, H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    In this article a new scheme is proposed to use mean supervector in text-prompted speaker verification system. In this scheme, for each month name a subsystem is constructed and a final score based on passphrase is computed by the combination of the scores of these subsystems. Results from the telephony dataset of Persian month names show that the proposed method significantly reduces EER in comparison with the-State-of-the-art State-GMM-MAP method. Furthermore, it is shown that based on training set and testing set we can use 12 models per speaker instead of 220. Therefore, this scheme reduces EER and computational burden. In addition, the use of HMM instead of GMM as words' model improves... 

    Hidden markov model-based speech enhancement using multivariate laplace and gaussian distributions

    , Article IET Signal Processing ; Volume 9, Issue 2 , 2015 , Pages 177-185 ; 17519675 (ISSN) Aroudi, A ; Veisi, H ; Sameti, H ; Sharif University of Technology
    Institution of Engineering and Technology  2015
    Abstract
    In this paper, statistical speech enhancement using hidden Markov model (HMM) is studied and new techniques for applying non-Gaussian distributions are proposed. The superiority of using non-Gaussian distributions in online adaptive noise suppression algorithms has been proven; however, in this study, this approach is formulated in an HMM-based mean-square error estimator (MMSE) estimator in which a priori models are trained in an off-line manner. In addition, an analytical study of using different distributions other than autoregressive (AR) Gaussian distribution, such as Laplace, is presented in order to construct an accurate HMM as a priori model for discrete Fourier transform and... 

    Multi-objective cordon price design to control long run adverse traffic effects in large urban areas

    , Article NETNOMICS: Economic Research and Electronic Networking ; Volume 16, Issue 1-2 , August , 2015 , pp 1–52 ; 13859587 (ISSN) Amirgholy, M ; Rezaeestakhruie, H ; Poorzahedy, H ; Sharif University of Technology
    Springer New York LLC  2015
    Abstract
    Pricing is seen as a viable alternative to manage the demand for transportation facilities. While supply increase might aggravate the problem, pricing is envisaged to relieve large cities from adverse traffic effects (congestion and pollution, among others). Nevertheless, pricing has its own drawbacks, often overlooked by the operators of the networks. It will cause changes in the travel behavior of the different groups and their demands (shoppers, retailers, and even basic businesses/ employees). This paper presents an extensive review of the subject, and an equilibrium model to estimate the long–run effects of a cordon pricing scheme. The problem of designing a price for a Central Business... 

    Chemometric-based determination of polycyclic aromatic hydrocarbons in aqueous samples using ultrasound-assisted emulsification microextraction combined to gas chromatography-mass spectrometry

    , Article Journal of Chromatography A ; Volume 1413 , September , 2015 , Pages 117-126 ; 00219673 (ISSN) Ahmadvand, M ; Sereshti, H ; Parastar, H ; Sharif University of Technology
    Elsevier  2015
    Abstract
    In the present research, ultrasonic-assisted emulsification-microextraction (USAEME) coupled with gas chromatography-mass spectrometry (GC-MS) has been proposed for analysis of thirteen environmental protection agency (EPA) polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Tetrachloroethylene was selected as extraction solvent. The main parameters of USAEME affecting the efficiency of the method were modeled and optimized using a central composite design (CCD). Under the optimum conditions (9 μL for extraction solvent, 1.15% (w/v) NaCl (salt concentration) and 10min for ultrasonication time), preconcentration factor (PF) of the PAHs was in the range of 500-950. In order to have a... 

    Second-order calibration for the determination of fatty acids in pomegranate seeds by vortex-assisted extraction-dispersive liquid-liquid micro-extraction and gas chromatography-mass spectrometry

    , Article RSC Advances ; Volume 5, Issue 15 , 2015 , Pages 11633-11643 ; 20462069 (ISSN) Ahmadvand, M ; Sereshti, H ; Parastar, H ; Sharif University of Technology
    2015
    Abstract
    Multivariate curve resolution-alternating least squares (MCR-ALS) as a second-order calibration algorithm was proposed for the simultaneous analysis of eighteen fatty acid methyl esters (FAMEs) in a standard mixture and pomegranate seed sample using vortex-assisted extraction-dispersive liquid-liquid microextraction (VAE-DLLME), followed by gas chromatography-mass spectrometry (GC-MS). The chemometric resolution, identification and quantification of the target FAMEs in the standard mixture and real sample (i.e., the pomegranate seed) were carried out successfully in the presence of some uncalibrated interferences. The lack of fit (LOF) and reverse match factor (RMF) were used for the... 

    Pattern recognition analysis of chromatographic fingerprints of Crocus sativus L. secondary metabolites towards source identification and quality control

    , Article Analytical and Bioanalytical Chemistry ; Volume 408, Issue 12 , 2016 , Pages 3295-3307 ; 16182642 (ISSN) Aliakbarzadeh, G ; Sereshti, H ; Parastar, H ; Sharif University of Technology
    Springer Verlag  2016
    Abstract
    Chromatographic fingerprinting is an effective methodology for authentication and quality control of herbal products. In the presented study, a chemometric strategy based on multivariate curve resolution-alternating least squares (MCR-ALS) and multivariate pattern recognition methods was used to establish a gas chromatography-mass spectrometry (GC-MS) fingerprint of saffron. For this purpose, the volatile metabolites of 17 Iranian saffron samples, collected from different geographical regions, were determined using the combined method of ultrasound-assisted solvent extraction (UASE) and dispersive liquid-liquid microextraction (DLLME), coupled with GC-MS. The resolved elution profiles and... 

    Improved optimal control technique for control of parallel three- phase inverters

    , Article 2009 International Conference on Electric Power and Energy Conversion Systems, EPECS 2009, Sharjah, 10 November 2009 through 12 November 2009 ; 2009 ; 9789948427155 (ISBN) pouya, H. R. N ; Mokhtari, H ; Sharif University of Technology
    2009
    Abstract
    This paper proposes a high performance voltage tracking and current sharing among parallel connected inverters by applying optimal control and minimizing the cost function. The control system forces the voltage of load to track the voltage reference, and the current of all inverters becomes equal. Therefore, both current sharing and voltage tracking are obtained. In addition, the smallest input energy and simplicity in control circuit are the other advantages of the suggested method. To show the performance of the proposed control scheme, the simulations with two-modular practical systems are performed and the results are provided. The results indicate that the control objectives are... 

    On the kinematic analysis of a spatial six-degree-of-freedom parallel manipulator

    , Article Scientia Iranica ; Volume 16, Issue 1 , 2009 , Pages 1-14 ; 10263098 (ISSN) Vakil, M ; Pendar, H ; Zohoor, H ; Sharif University of Technology
    2009
    Abstract
    In this paper, a novel spatial six-degree-of freedom parallel manipulator actuated by three base-mounted partial spherical actuators is studied. This new parallel manipulator consists of a base platform and a moving platform, which are connected by three legs. Each leg of the manipulator is composed of a spherical joint, prismatic joint and universal joint. The base-mounted partial spherical actuators can only specify the direction of their corresponding legs. In other words, the spin of each leg is a passive degree-of-freedom. The inverse pose and forward pose of the new mechanism are described. In the inverse pose kinematics, active joint variables are calculated with no need for...