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    On the Flutter of Swept Taper Wing in Subsonic Compressible Flow Considering Effect of Fuel Sloshing in External Stores

    , M.Sc. Thesis Sharif University of Technology Beheshtinia, Farshad (Author) ; Dehghani Firoozabadi, R (Supervisor)
    Abstract
    In the present work, the aeroelastic stability analysis for the swept taper wing and external fuel tank combination system in subsonic compressible flow are represented. The wing structure is modeled by using the Euler-Bernoulli beam theory. Fuel sloshing is modeled by using an equivalent mechanical mass-spring-damper model. Modal analysis technique is used to drive the structural equations of motion of the system. Aeorodynamic of wing is modeled by using index aerodynamic that has been dived by Marzocca and a slender body aerodynamic theory for the external fuel tank are used. For stability analysis, k-method redrived for a case that structural damping there is. The effects of the external... 

    Viscous damping effect on the aeroelastic stability of subsonic wings: Introduction of the U–K method

    , Article Journal of Fluids and Structures ; Volume 73 , 2017 , Pages 1-15 ; 08899746 (ISSN) Beheshtinia, F ; Dehghani Firouz Abadi, R ; Rahmanian, M ; Sharif University of Technology
    2017
    Abstract
    This study aims at introduction of a novel method for evaluating the effect of viscous damping on the aeroelastic stability boundaries. The K-method is well-known for being one of the fastest methods in determining the instability conditions (i.e. critical speed and its corresponding frequency). However, formulation of the K-method is developed for aeroelastic systems without viscous damping and solution is valid where the introduced artificial damping is zero. Taking into account the framework of the K-method in general, this study has tried to remove the major shortcoming of the K-method, i.e. investigation of the effect of viscous damping on the aeroelastic stability boundaries. The... 

    Effect of heating profile on desorption curve in temperature programmed desorption analysis: Case study of acid sites distribution of SAPO-34

    , Article Journal of Porous Materials ; Volume 16, Issue 5 , 2009 , Pages 599-603 ; 13802224 (ISSN) Izadbakhsh, A ; Farhadi, F ; Khorasheh, F ; Yan, Z. F ; Sharif University of Technology
    2009
    Abstract
    Comparison of the traditional linear heating method of TPD with an original stepwise heating scheme was reported for the first time. Stepwise heating TPD was carried out by keeping the temperature constant as soon as ammonia desorption signal rises until the signal returns to the baseline. More ammonia desorption peaks on a SAPO-34 catalyst were identified using TPD with stepwise heating. The effect of temperature ramp on desorption peak broadening in TPD curve was also addressed. The more distinct ammonia desorption peaks in stepwise TPD indicates that ammonia adsorbs in about five or six different ways on SAPO-34, and attribution of different adsorptions may be explained considering some... 

    Theoretical and experimental study of cascade solar stills

    , Article Solar Energy ; Volume 90 , April , 2013 , Pages 205-211 ; 0038092X (ISSN) Ziabari, F. B ; Sharak, A. Z ; Moghadam, H ; Tabrizi, F. F ; Sharif University of Technology
    2013
    Abstract
    Most part of Iran is dominated by arid and semi-arid areas due to low annual rainfall. The need for production of fresh water from brackish water is considerably high, especially in dry regions. In this study 1 month daily-based experimental data from a solar still site has been reported. The technical and operational problems of this site which finally contributed to the total cease of the site are described. Then a detailed analysis is investigated on progress of a prototype which constructed in order to solve the site's problems. The results of 1 month of experimental data of the final design showed that the last prototype could be used to solve the current problems of the site. The... 

    Application of a continuous kinetic model for the hydrocracking of vacuum gas oil

    , Article Petroleum Science and Technology ; Vol. 32, Issue. 18 , 2014 , Pages 2245-2252 ; ISSN: 10916466 Arefi, A ; Khorasheh, F ; Farhadi, F ; Sharif University of Technology
    2014
    Abstract
    Hydrocracking is one of the most versatile petroleum refining processes for production of valuable products including gasoline, gas oil, and jet fuel. In this paper, a five-parameter continuous lumping model was used for kinetic modeling of hydrocracking of vacuum gas oil (VGO). The model parameters were estimated from industrial data obtained from a fixed bed reactor operating at an average temperature of 400°C and residence time of 0.3 h. Product distributions were obtained in terms of the weight fraction of various boiling point cuts. The model parameters were estimated using the Nelder-Mead optimization procedure and were correlated with temperature. Comparison of experimental and... 

    An improved methodology for design of custom-made hip prostheses to be fabricated using additive manufacturing technologies

    , Article Rapid Prototyping Journal ; Volume 18, Issue 5 , 2012 , Pages 389-400 ; 13552546 (ISSN) Rahmati, S ; Abbaszadeh, F ; Farahmand, F ; Sharif University of Technology
    Emerald  2012
    Abstract
    Purpose - The purpose of this paper is to present an improved methodology for design of custom-made hip prostheses, through integration of advanced image processing, computer aided design (CAD) and additive manufacturing (AM) technologies. Design/methodology/approach - The proposed methodology for design of custom-made hip prostheses is based on an independent design criterion for each of the intra-medullary and extra-medullary portions of the prosthesis. The intra-medullar part of the prosthesis is designed using a more accurate and detailed description of the 3D geometry of the femoral intra-medullary cavity, including the septum calcar ridge, so that an improved fill and fit performance... 

    Evaluation and enhancing of operational performance and training objective in accordance with Line Operations Safety Audit (LOSA)

    , Article International Air Safety Seminar Proceedings, 1 November 2011 through 3 November 2011 ; November , 2011 , Pages 78-99 ; 02705176 (ISSN) ; 9781618393975 (ISBN) Khoshkhoo, R ; Goodarzi, F ; Sharafbafi, F ; Sharif University of Technology
    2011

    Real-time impulse noise suppression from images using an efficient weighted-average filtering

    , Article IEEE Signal Processing Letters ; Volume 22, Issue 8 , 2015 , Pages 1050-1054 ; 10709908 (ISSN) Hosseini, H ; Hessar, F ; Marvasti, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    In this letter, we propose a method for real-time high density impulse noise suppression from images. In our method, we first apply an impulse detector to identify the corrupted pixels and then employ an innovative weighted-average filter to restore them. The filter takes the nearest neighboring interpolated image as the initial image and computes the weights according to the relative positions of the corrupted and uncorrupted pixels. Experimental results show that the proposed method outperforms the best existing methods in both PSNR measure and visual quality and is quite suitable for real-time applications  

    Kinetic modeling of pyrolysis of scrap tires

    , Article Journal of Analytical and Applied Pyrolysis ; Volume 84, Issue 2 , 2009 , Pages 157-164 ; 01652370 (ISSN) Mazloom, G ; Farhadi, F ; Khorasheh, F ; Sharif University of Technology
    2009
    Abstract
    The disposal of used tires is a major environmental problem. With increasing interest on recovery of wastes, pyrolysis is considered as an alternative process for recovering some of the value in scrap tires. An accurate kinetic model is required to predict product yields during thermal or catalytic pyrolysis of scrap tires. Pyrolysis products contain a variety of hydrocarbons over a wide boiling range. A common approach for kinetic modeling of such complex systems is lumping where each lump is defined by a boiling point range. Available experimental data for thermal and catalytic pyrolysis of scrap tires from the literature were used to evaluate two types of lumping models; discrete and... 

    Determine oil content in petroleum waxes

    , Article Hydrocarbon Processing ; Volume 85, Issue 6 , 2006 , Pages 95-97 ; 00188190 (ISSN) Mafi, M ; Yazdani, F ; Farhadi, F ; Sharif University of Technology
    2006

    Analytical modeling of variable-reluctance tubular resolver based on magnetic equivalent circuit and conformal mapping

    , Article IEEE Transactions on Instrumentation and Measurement ; Volume 70 , 2021 ; 00189456 (ISSN) Keyvannia, A ; Zare, F ; Tootoonchian, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    Abstract
    Compared with flat linear structures, tubular linear machines do not face edge effects, making their performance better than their flat counterparts. In this article, a novel linear variable-reluctance resolver with tubular configuration is proposed. To optimize the design of an electromagnetic structure, modeling methods are used. Thus, in this article, an analytical model for the proposed resolver is presented. This model is based on the magnetic equivalent circuit (MEC) method and is considerably less time-consuming than finite element analysis (FEA), yet provides accurate results. A conformal mapping is employed to compute the permeance of the air-gap. The proposed model is then utilized... 

    Information and the Brukner-Zeilinger interpretation of quantum mechanics: A critical investigation

    , Article Foundations of Physics Letters ; Volume 19, Issue 1 , 2006 , Pages 1-20 ; 08949875 (ISSN) Shafiee, A ; Safinejad, F ; Naqsh, F ; Sharif University of Technology
    2006
    Abstract
    In Brukner and Zeilinger's interpretation of quantum mechanics, information is introduced as the most fundamental notion and the finiteness of information is considered as an essential feature of quantum systems. They also define a new measure of information which is inherently different from the Shannon information and try to show that the latter is not useful in defining the information content in a quantum object. Here, we show that there are serious problems in their approach which make their efforts unsatisfactory. The finiteness of information does not explain how objective results appear in experiments and what an instantaneous change in the so-called information vector (or catalog of... 

    Key parameters in hydrothermal synthesis and characterization of low silicon content SAPO-34 molecular sieve

    , Article Microporous and Mesoporous Materials ; Volume 126, Issue 1-2 , 2009 , Pages 1-7 ; 13871811 (ISSN) Izadbakhsh, A ; Farhadi, F ; Khorasheh, F ; Sahebdelfar, S ; Asadi, M ; Yan, Z. F ; Sharif University of Technology
    2009
    Abstract
    Low silicon content SAPO-34 was successfully synthesized using the conventional hydrothermal crystallization in the static condition. Effects of different synthesis conditions including crystallization temperature and the silicon source were investigated through X-ray diffraction patterns. It was concluded that the silicon source had a significant effect on silicon incorporation into the alumino-phosphate building blocks in the course of crystallization. Using precipitated silica instead of silica sol resulted in the formation of impurities of alumino-phosphates phases whose crystalline structures collapse at the high temperature of calcination. For the low silicon SAPO-34 synthesis, the... 

    On the Finiteness of Noetherian Rings with Finitely Many Regular Elements

    , Article Communications in Algebra ; Vol. 42, issue. 7 , 2014 , pp. 2869-2870 ; ISSN: 00927872 Akbari, S ; Heydari, F
    2014
    Abstract
    Let R be a left Noetherian ring and ZD(R) be the set of all zero-divisors of R. In this paper, it is shown that if RZD(R) is finite, then R is finite  

    Precision of direction of arrival (DOA) estimation using novel three dimensional array geometries

    , Article AEU - International Journal of Electronics and Communications ; Volume 75 , 2017 , Pages 35-45 ; 14348411 (ISSN) Poormohammad, S ; Farzaneh, F
    Elsevier GmbH  2017
    Abstract
    Numerous methods for direction of arrival (DOA) estimation, used in smart antennas have been already reported in previous studies. The precision of DOA estimation depends on the choice of the algorithm and the geometrical configuration of the antenna array. In this work, the performance of new geometrical configurations, i.e. 2D with equal area and 3D with equal volume including circular, square, triangular, hexagonal and star geometries, with equal number of antenna elements, are examined and compared to each other to find the most proper geometry. Monte-Carlo simulations are performed to evaluate the DOA precision of the proposed arrays using the MUSIC algorithm. It is shown that in three... 

    Detecting matrices for random CDMA systems

    , Article 2013 20th International Conference on Telecommunications, ICT 2013 ; 2013 Sedaghat, M. A ; Bateni, F ; Marvasti, F ; Sharif University of Technology
    IEEE Computer Society  2013
    Abstract
    This paper studies detecting matrices in random dense and sparse Code Division Multiple Access (CDMA) systems. Detecting matrices were originally introduced in the coin weighing problem. Such matrices can be used in CDMA systems in over-loaded scheme where the number of users is greater than the number of chips. We drive some conditions in the large system limit for binary and bipolar random CDMA systems to ensure that any random matrix is a detecting matrix. Furthermore, we extend our results to sparse random ternary matrices that have been using in the sparse CDMA literature. Finally, a construction method for the sparse detecting matrices is introduced  

    A neuro-optimal approach for thrust-insensitive trajectory planning

    , Article Aircraft Engineering and Aerospace Technology ; Volume 81, Issue 3 , 2009 , Pages 212-220 ; 00022667 (ISSN) Pourtakdoust, S. H ; Pazooki, F ; Noushabadi, F ; Sharif University of Technology
    2009
    Abstract
    Purpose - The purpose of this paper is to devise a new approach to synthesize closed-loop feedback guidance law for online thrust- insensitive optimal trajectory generation utilizing neural networks. Design/methodology/approach - The proposed methodology utilizes an open- loop variational formulation that initially determines optimal launch/ ascent trajectories for various scenarios of known uncertainties in the thrust profile of typical solid propellant engines. These open-loop optimized trajectories will then provide the knowledge base needed for the subsequent training of a neural network. The trained network could eventually produce thrust-insensitive closed-loop optimal guidance laws... 

    Design oriented technique for mitigating position error due to shaft run-out in sinusoidal-rotor variable reluctance resolvers

    , Article IET Electric Power Applications ; 2017 , Pages 132-141 ; 17518660 (ISSN) Nasiri Gheidari, Z ; Tootoonchian, F ; Zare, F ; Sharif University of Technology
    2017
    Abstract
    Variable reluctance (VR) resolvers have some distinguish features over wounded rotor resolvers that make them suitable for industrial applications. Among different types of VR resolvers, sinusoidal-rotor resolvers are preferred due to simple structure and high performance under eccentricities. However, their accuracy is affected by inevitable run-out error. As they work based on sinusoidal variation of coupling area between stator and rotor and under run-out error the coupling area is impaired. Hence, in this study, a new disk shape configuration is proposed for sinusoidal-rotor resolver that is robust against run-out error. Geometrical dimensions are calculated based on optimisations to... 

    The seismic performance of K-braced cold-formed steel shear panels with improved connections

    , Article Journal of Constructional Steel Research ; Volume 135 , 2017 , Pages 56-68 ; 0143974X (ISSN) Pourabdollah, O ; Farahbod, F ; Rahimzadeh Rofooei, F ; Sharif University of Technology
    Elsevier Ltd  2017
    Abstract
    In this paper the performance of light weight K-braced cold formed steel (CFS) shear panels under cyclic loading is experimentally evaluated. It is generally known that the brace-stud connection details has an important effect on the performance of the braced CFS shear panels in terms of lateral stiffness, energy dissipation, and ductility factor. In this study, four full-scale, 2.4 m × 2.4 m, braced CFS shear panels made of C-sections were tested. It was observed that proper modification of the currently utilized braced to stud connections in K-braced, CFS shear panels could enhance their performance considerably by increasing their ultimate shear resistance up to 7 folds. Furthermore,... 

    Multi-GNSS constellation fusion based on statistical features of positioning error

    , Article 26th Iranian Conference on Electrical Engineering, ICEE 2018, 8 May 2018 through 10 May 2018 ; 2018 , Pages 725-730 ; 9781538649169 (ISBN) Abolfathi Momtaz, A ; Behnia, F ; Marvasti, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    With the advent of new positioning services, one can reach more satellites these days to find his position. Using a combination of satellites which belong to different constellations needs some considerations like addressing biases between their time references. Each constellation has progressed to the point that they have enough satellites to provide accurate position separately. According to this fact, we propose to find the position in each constellation and fusion their results in a way that final position has the minimum possible variance instead of combining the constellations in a satellite level and dealing with inter system biases. Experimental studies are conducted based on IGS...