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    Modeling the acoustic effects on droplet vaporization in a laboratory pulse combustor

    , Article American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED ; Volume 253 , 2000 , Pages 1077-1084 ; 08888116 (ISSN) Maghami, E. G ; Akbari, P ; Ghafourian, A ; Sharif University of Technology
    2000
    Abstract
    Both theoretical and experimental analysis of acoustics fields effects on droplet vaporization are presented. Theoretical investigation is based on droplet vaporization without combustion in both steady and longitudinal acoustic fields with variable properties in one dimension. An axisymmetric pulse combustor is developed for simulating the longitudinal acoustic field. A spray system is used for producing water droplets. Controllable parameters of the system are the hot air and liquid injection velocities, direction of injection and frequency of acoustic oscillation. The theoretical results indicate that the evaporation time decreases up to 30 percent in an acoustic field in comparison to... 

    Design Optimization of Linear Variable-Reluctance Resolver for Higher Accuracy and Smaller Size

    , Article IEEE Sensors Journal ; Volume 23, Issue 15 , 2023 , Pages 16764-16771 ; 1530437X (ISSN) Ghaem Maghami, M ; Nasiri Gheidari, Z ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2023
    Abstract
    Linear variable reluctance (VR) resolvers offer robustness and affordability in comparison with wound mover sensors. However, the accuracy of linear sensors is influenced by geometrical dimensions and the longitudinal end effect. In this article, the end effect was compensated by altering the teeth's shape using the tooth-pairing method. This altered shape could achieve much better accuracy. Furthermore, the influence of many different geometrical dimensions and shapes of teeth and yoke were examined using finite-element analysis (FEA). In addition, the results of this analysis show a trade-off between the accuracy and weight of the resolver in some cases. To verify the correctness of the... 

    Provide a Model for the Sitting of Hydroelectric Power Plants Using GIS and Multiple Criteria Decision FTOPSIS: A Case From Kelas Basin

    , M.Sc. Thesis Sharif University of Technology Darban Maghami, Alireza (Author) ; Shamsai, Abolfazl (Supervisor)
    Abstract
    Nowadays due to increasing environmental considerations and effort to reducing of the fossil fuels consumption, the necessity of hydroelectric power plants development is emerged. The purpose of this study is to suggest a method of spatial analysis for finding sites with appropriate potential for construction of these power plants, using TOPSIS and GIS. In this research, using the Python programming language, in software environment of Arc GIS version 9.3, local hydrological model was generated using the DEM layer and using of streams ordering methods, the overall situation along the river were processed. In the next step, with using of fuzzy TOPSIS algorithm implementation in software... 

    Steganography Based on Sparse Decomposition

    , Ph.D. Dissertation Sharif University of Technology Ahani, Soodeh (Author) ; Ghaem Maghami, Shahrokh (Supervisor)
    Abstract
    The goal of this thesis is using sparse decomposition to design secure steganography algorithms to insert secret data into the different cover signals. We propose data embedding in higher semantic levels of the cover signal to reach this goal. Sparse decomposition represents a signal as a linear combination of its structural elements. Data insertion into the sparse coefficients slightly changes the effect of structural elements in the signal representation. So, quality of the stego signal is preserved and such a steganography method leads to higher imperceptibility. In addition, data insertion into the higher semantic levels leads to the higher undetectability. Steganalyzers use statistical... 

    Speech Enhancement Using Deep Neural Networks in Non-stationary Noise Environment

    , M.Sc. Thesis Sharif University of Technology Hosseini, Ehsan (Author) ; Ghaem Maghami, Shahrokh (Supervisor)
    Abstract
    Before performing any operation on a speech signal, it is necessary to properly remove the environmental noise existing on it. Noise Canceling Operation on Speech Signal is called speech enhancement. Up to now, many studies have been conducted on various ways to enhance the speech signal. Among the existing methods, statistical methods have proven to be superior to others. In all noise removal methods, the main challenge is that most noises are non-stationary. Since most of the noises in the environment are non-stationary, we are still looking for the better ways to remove them. With the advent of deep neural networks and their successful results in areas such as machine learning, a method... 

    Development of a Control Algorithm for Functional Electrical Stimulation to Achieve Smooth Motion

    , M.Sc. Thesis Sharif University of Technology Ghaem Maghami, Horieh (Author) ; Behzadipour, Saeed (Supervisor)
    Abstract
    The use of functional electrical stimulation after spinal cord injury is one of the most effective ways to prevent muscle atrophy.” Enzymes construction set, torque output increases and improved fatigue resistance”.
    Functional electrical stimulation devices help in the operation of a muscle by applying a weak electrical current. This stimulation causes muscle contraction. In other words, it replaces the neural signals required to move the limb that cannot be produced due to causes such as spinal cord injury (SCI) orsecondary problems that arise after SCI.
    One of the drawbacks of using FES is jerky motions in the muscles and limps. Such movements are not only harmful, but results in... 

    A catalyzed method to remove polychlorinated biphenyls from contaminated transformer oil

    , Article Environmental Science and Pollution Research ; 2021 ; 09441344 (ISSN) Maghami, A ; Gholipour Zanjani, N ; Khorasheh, F ; Arjmand, M ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    Abstract
    The disposal of polychlorinated biphenyls (PCBs) as persistent organic pollutants from the environment has been normally performed by isolation from soil or water because of their biological activity and toxic potential. In the present investigation, catalytic hydrodehalogenation was used to detoxify PCBs-contaminated transformer oil. All reactions were directed on an oil containing 11.09 wt% of PCBs utilizing palladium supported on multi-walled carbon nanotubes (Pd/MWCNTs). The amount of hexa-chlorine homologues reduced considerably from 5.07% to less than 800 ppm utilizing HDC at the atmosphere of argon. Moreover, the amounts of long half-lives and bioaccumulative congener of PCB 153... 

    A catalyzed method to remove polychlorinated biphenyls from contaminated transformer oil

    , Article Environmental Science and Pollution Research ; Volume 29, Issue 9 , 2022 , Pages 13253-13267 ; 09441344 (ISSN) Maghami, A ; Gholipour Zanjani, N ; Khorasheh, F ; Arjmand, M ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2022
    Abstract
    The disposal of polychlorinated biphenyls (PCBs) as persistent organic pollutants from the environment has been normally performed by isolation from soil or water because of their biological activity and toxic potential. In the present investigation, catalytic hydrodehalogenation was used to detoxify PCBs-contaminated transformer oil. All reactions were directed on an oil containing 11.09 wt% of PCBs utilizing palladium supported on multi-walled carbon nanotubes (Pd/MWCNTs). The amount of hexa-chlorine homologues reduced considerably from 5.07% to less than 800 ppm utilizing HDC at the atmosphere of argon. Moreover, the amounts of long half-lives and bioaccumulative congener of PCB 153... 

    Audio-visual Speaker Verification Using Identity Based Articulatory Features

    , M.Sc. Thesis Sharif University of Technology Keshavarz Chafjiri, Amir Hossein (Author) ; Ghaem Maghami, Shahrokh (Supervisor)
    Abstract
    Many companies feel the need of automatic person identification for tracking entrance and exit of their employers. This system will help the company in reducing security costs, waste of time and increasing security. In this thesis a novel idea for 3d convolutional neural network text independent speaker verification system will introduced. Since many scenarios visionary data like lip motion, besides speech data, is available, in this thesis both of these data streams are used for developing designed speaker verification system. Multimodalily helps the verification system to be more robust to the noise and attacks. One of the main challenges in designing multimodal neural network speaker... 

    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) Zareh, S. H ; 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) Dashti, M ; 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) Dashti, M ; 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) Dolatabad, M.R ; 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 Pirjalili, A ; 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... 

    Gum tragacanth gels as a new supporting matrix for immobilization of whole-cell

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 24, Issue 4 , 2005 , Pages 1-7 ; 10219986 (ISSN) Otady, M ; Vaziri, A ; Seifkordi, A. A ; Kheirolomoom, A ; Sharif University of Technology
    2005
    Abstract
    We introduce a new smooth, non-toxic, biocompatible method for cross-linking of gum tragacanth (GT), a polysaccharide of natural origin, in order to serve as a new supporting matrix for immobilization systems. The modified gum is used as a matrix for the catalysis of the conversion of benzyl penicillin to 6-aminopenicillanic acid (6-APA) by means of Escherichia coli ATCC11105 with penicillin G acylase (PGA) activity. The results show that GT beads can not only serve as a proper matrix for immobilization, but show enhanced hydrolysis rate and stability compared to other immobilization systems used for this reaction. This signifies the potential of GT as a biocompatible matrix for... 

    True Class-E Design For Inductive Coupling Wireless Power Transfer Applications

    , Article 30th International Conference on Electrical Engineering, ICEE 2022, 17 May 2022 through 19 May 2022 ; 2022 , Pages 864-868 ; 9781665480871 (ISBN) Haeri, A. A. R ; Safarian, A ; Fotowat Ahmady, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2022
    Abstract
    The Class-E power amplifier has been widely studied and formulated in the literature. Although the majority of reported inductive coupling wireless power transfer (WPT) systems use a class-E power amplifier for driving the primary coil, still there is a lack of a comprehensive study on class-E circuit dedicated to WPT, providing a set of closed form design equations for proper class-E operation. This paper presents the required design equations needed to design a 'true' class-E circuit for WPT applications. Equations for the series-tuned secondary coil WPT system are presented, as well as two different design procedures for the parallel-tuned secondary coil. The derived equations have been... 

    Crashworthiness determination of side doors and B pillar of a vehicle subjected to pole side impact

    , Article Applied Mechanics and Materials ; Vol. 663, issue , 2014 , p. 552-556 Lilehkoohi, A. H ; Faieza, A. A ; Sahari, B. B ; Nuraini, A. A ; Halali, M ; Sharif University of Technology
    2014
    Abstract
    Pole Side Impact Tes is one out of three crash tests described by Euro NCAP standard for star rating of a vehicle and is required for assessing the Adult Occupant Protection. In this paper the goal is to determine the crashworthiness of side doors and B pillar in a Pole Side Impact Test based on Euro New Car Assessment Program (Euro-NCAP) using computer and simulation method. In this matter, a vehicle model has been prepared and meshed using Hypermesh and CATIA. The velocity of 29 km/h has been assigned to the vehicle which was on top of a cart while the pole has been assigned as a rigid static object based on Euro NCAP requirements specifically. Results show that different amounts of energy... 

    Investigation of Thickness Influences On Energy Absorption For Side Doors And B Pillar In Euro NCAP Pole Side Impact Test

    , Article Applied Mechanics and Materials ; Vol. 663, issue , Oct , 2014 , p. 585-589 Lilehkoohi, A. H ; Faieza, A. A ; Sahari, B. B ; Nuraini, A. A ; Halali, M ; Sharif University of Technology
    2014
    Abstract
    To assess a car under the Euro New Car Assessment Program (Euro-NCAP), Adult Occupant Protection is one out of three parameters which need to be calculated with a weight factor of 50% while the other parameters, Child Occupant Protection and Pedestrian Occupant Protection, have a weight factor of 20%. The Pole Side Impact Test, beside two other tests, Side and Front Impact, is also required to calculate the Adult Occupant Protection. It shows how important the Pole Side Impact Test is and what an effective role it has in the car rating assessment. In this paper, the objective is to evaluate the effect of thickness on the energy absorbed by the side doors and the B pillar and its... 

    Crashworthiness determination for front and rear doors and B pillar subjected to side impact crash by a mobile deformable barrier

    , Article Advanced Science Letters ; Volume 19, Issue 2 , 2013 , Pages 392-395 ; 19366612 (ISSN) Lilehkoohi, A. H ; Faieza, A. A ; Sahari, B. B ; Nuraini, A. A ; Halali, M ; Sharif University of Technology
    2013
    Abstract
    In Euro NCAP standard, adult protection is one of the most important rating scores with 50% weight factor while child protection and pedestrian protection are accounted into consideration with 20% weight factor. For adult protection testing, three tests are required to perform: (1) side impact, (2) pole impact, (3) front impact. In the side impact test, dummy's head, chest, shoulder, thorax, ribs, abdomen, pelvic and femur must be studied to evaluate the rating score. Crashworthiness of a car during side impact can describe the score rated for that car. In this paper the goal is to determine the crashworthiness of side doors and B-pillar in side impact crash est by simulation using LS DYNA... 

    Effect of material and thickness of side doors and B pillar on crashworthiness in euro NCAP side impact crash test

    , Article Advanced Science Letters ; Volume 19, Issue 2 , 2013 , Pages 420-424 ; 19366612 (ISSN) Lilehkoohi, A. H ; Faieza, A. A ; Sahari, B. B ; Nuraini, A. A ; Halali, M ; Sharif University of Technology
    2013
    Abstract
    In side impact test which is one out of three tests of Euro NCAP standard, front and rear doors and B pillar are most absorbance parts among vehicle body parts. Passengers are highly in danger while side crash, because of the distance between passenger's head and vehicle body. In this paper effect of material and thickness of doors and B-pillar and their absorbed energy during crash and improvement of its crashworthiness with respect to light weight design are studied using LS DYNA solver. The objective of this paper is to propose a material for doors and B-pillar with a specified thickness to achieve maximum absorbed energy and minimum weight. The shape of the doors and B-pillar remains...