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    Products of rotations by a given angle in the orthogonal group

    , Article Bulletin of the Australian Mathematical Society ; 2017 , Pages 1-5 ; 00049727 (ISSN) Mahmoudi, M. G ; Sharif University of Technology
    For every rotation (Formula presented.) of the Euclidean space (Formula presented.) ((Formula presented.)), we find an upper bound for the number (Formula presented.) such that (Formula presented.) is a product of (Formula presented.) rotations by an angle (Formula presented.) ((Formula presented.)). We also find an upper bound for the number (Formula presented.) such that (Formula presented.) can be written as a product of (Formula presented.) full rotations by an angle (Formula presented.). © 2017 Australian Mathematical Publishing Association Inc  

    products of rotations by a given angle in the orthogonal group

    , Article Bulletin of the Australian Mathematical Society ; Volume 97, Issue 2 , 2018 , Pages 308-312 ; 00049727 (ISSN) Gholamzadeh Mahmoudi, M ; Sharif University of technology
    Cambridge University Press  2018
    For every rotation of the Euclidean space ℝ(n≥3), we find an upper bound for the number such that is a product of rotations by an angle α( 0<≤π). We also find an upper bound for the number such that ρ can be written as a product of full rotations by an angle α. © 2017 Australian Mathematical Publishing Association Inc  

    On the existence of chaotic circumferential waves in spinning disks

    , Article Chaos ; Volume 17, Issue 2 , 2007 ; 10541500 (ISSN) Angoshtari, A ; Jalali, M. A ; Sharif University of Technology
    American Institute of Physics Inc  2007
    We use a third-order perturbation theory and Melnikov's method to prove the existence of chaos in spinning circular disks subject to a lateral point load. We show that the emergence of transverse homoclinic and heteroclinic points lead, respectively, to a random reversal in the traveling direction of circumferential waves and a random phase shift of magnitude π for both forward and backward wave components. These long-term phenomena occur in imperfect low-speed disks sufficiently far from fundamental resonances. © 2007 American Institute of Physics  

    Phenol biodegradation by rotating biological contactor

    , Article Biochemical Engineering Journal ; Volume 11, Issue 1 , 2002 , Pages 19-23 ; 1369703X (ISSN) Alemzadeh, I ; Vossoughi, F ; Houshmandi, M ; Sharif University of Technology
    This study presents the removal performance of phenol in a three-stages cross flow laboratory-scale rotating biological contactor (RBC). The impact of major process and operating variables, such as input hydraulic loading (HL), input COD loading, and temperature of wastewater on the total removal efficiency of the system were examined. It was observed that the phenol removal performance worsened when the HL increased, and optimum total phenol removal efficiency of 99.9% was observed at loading of 4 × 10-3 m-3 m-2 per day and COD concentration of 800 mg dm-3. On the basis of overall treatment of phenol containing wastewater in the RBC, the optimal removal performance was noted at the end of... 

    The vibration-rotation kinetic energy operator for sequentially bonded tetra-atomic molecules in internal coordinates

    , Article Molecular Physics ; Volume 105, Issue 17-18 , 2007 , Pages 2269-2278 ; 00268976 (ISSN) Ebrahimi, H ; Tafazzoli, M ; Sharif University of Technology
    An exact vibration-rotation kinetic energy operator for polyatomic molecules has been obtained. Using this Hamiltonian for sequentially bonded tetra-atomic molecules, all rovibrational terms have been derived with internal coordinates as the vibrational variables. The present approach is greatly simplified with less algebra compared with conventional methods. Also, simple and explicit expressions for the vibration-rotation coupling terms in internal coordinates are presented  

    Effects of geometric factors and material properties on stress behavior in rotating disk

    , Article Indian Journal of Science and Technology ; Vol. 7, issue. 1 , Jan , 2014 , p. 1-6 Monfared, V ; Hassan, M ; Daneshmand, S ; Taheran, F ; Ghaffarivardavagh, R ; Sharif University of Technology
    In this study, effects of geometric factors and material properties are investigated on stress behavior of circular rotating disk with constant rotation in various industrial mechanisms using equilibrium equations, geometric relations and stress functions. In this way, research on a thin uniform and homogeneous circular disk under constant rotation is considered. The rotating motion produces centrifugal acceleration on each element of the rotating disk, and this rotating motion becomes the source of external loading for the mentioned problem. Additional exterior loadings are not assumed in this problem. It is comfortable to handle the centrifugal force loading by relating it to a body force... 

    Improving productivity through increased capacity

    , Article World Cement ; Volume 34, Issue 7 , 2003 , Pages 99-105 ; 02636050 (ISSN) Safaieh, M. R ; Kakuei, A ; Sharif University of Technology
    The upgradation of the Kerman cement plant in Iran was discussed. It produces type 2,5 and pozzolanic cements which constitute almost 4.2% of the cement used in Iran. A short description of the process used, and some observations and recommendations about the plant were also provided  

    Geography of the rotational resonances and their stability in the ellipsoidal full two body problem

    , Article Icarus ; Volume 265 , 2016 , Pages 175-186 ; 00191035 (ISSN) Jafari Nadoushan, M ; Assadian, N ; Sharif University of Technology
    Academic Press Inc 
    A fourth-order Hamiltonian describing the planar full two body problem is obtained, allowing for a mapping out of the geography of spin-spin-orbit resonances. The expansion of the mutual potential function up to the fourth-order results in the angles to come through one single harmonic and consequently the rotation of both bodies and mutual orbit are coupled. Having derived relative equilibria, stability analysis showed that the stability conditions are independent of physical and orbital characteristics. Simultaneously chaotic motion of bodies is investigated through the Chirikov diffusion utilizing geographic information of the complete resonances. The results show that simultaneous chaos... 

    3-point RANSAC for fast vision based rotation estimation using GPU technology

    , Article IEEE International Conference on Multisensor Fusion and Integration for Intelligent Systems9 February 2017 ; 2017 , Pages 212-217 ; 9781467397087 (ISBN) Kamran, D ; Manzuri, M. T ; Marjovi, A ; Karimian, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    In many sensor fusion algorithms, the vision based RANdom Sample Consensus (RANSAC) method is used for estimating motion parameters for autonomous robots. Usually such algorithms estimate both translation and rotation parameters together which makes them inefficient solutions for merely rotation estimation purposes. This paper presents a novel 3-point RANSAC algorithm for estimating only the rotation parameters between two camera frames which can be utilized as a high rate source of information for a camera-IMU sensor fusion system. The main advantage of our proposed approach is that it performs less computations and requires fewer iterations for achieving the best result. Despite many... 

    Electrochemical Deposition of Composite Coatings of Nickel - Silicon Carbide Under Pulsed Current Using a Rotating Disk Electrode

    , M.Sc. Thesis Sharif University of Technology Zarghami, Vahid (Author) ; Ghorbani, Mohammad (Supervisor)
    Ni-SiC composite coatings are widely used in industry (equipment high wear resistance coatings, corrosion resistant coatings, ship and boiler coatings, . . . ). Its unique properties in high wear resistance, corrosion resistance and tribological properties, researchers tend to investigate this coating. This study covers Ni-SiC composite coating under pulsed current using a rotating disk electrode to achieve optimal conditions in synthsis process, increaseing hardness and resistance to corrosion in coatings.waats' bath established for electrodeposition in this research. Bath parameters, current parameters and hydrodynamic of solution is examined. Changing of current type from direct current... 

    PRI (Palm Rotation Indicator): a metric for postural stability in dynamic nonprehensile manipulation [electronic resource]

    , Article Journal of MECHANIKA ; 2012, Vol. 18, No. 4, pp. 461-466 Beigzadeh, B. (Borhan) ; Meghdar, Ali ; Sohrabpour, Saeed ; Sharif University of Technology
    In this study, we discuss the postural stability of a nonprehensile manipulation problem, which deals with multibody objects. As a metric for postural stability, we define PRI. Then, the system is posturally stable, if PRI is inside the convex hull of the object-manipulator contact surface. We then discuss that dynamic biped locomotion is a special case of dynamic nonprehensile manipulation in all aspects; we prove that ZMP (zero-moment point) and FRI (zoot rotation indicator) are special cases of PRI (palm rotation indicator). Simulations and experiments corresponding to simple examples support the results  

    Relativistic rotation curve for cosmological structures

    , Article International Journal of Modern Physics D ; Vol. 23, Issue. 9 , 2014 ; ISSN: 02182718 Razbin, M ; Firouzjaee, J. T ; Mansouri, R ; Sharif University of Technology
    Using a general relativistic exact model for spherical structures in a cosmological background, we have put forward an algorithm to calculate the test particle geodesics within such cosmological structures in order to obtain the velocity profile of stars or galaxies. The rotation curve thus obtained is based on a density profile and is independent of any mass definition which is not unique in general relativity. It is then shown that this general relativistic rotation curves for a toy model and a NFW density profile are almost identical to the corresponding Newtonian one, although the general relativistic masses may be quite different  

    Online visual gyroscope for autonomous cars

    , Article 24th Iranian Conference on Electrical Engineering, ICEE 2016, 10 May 2016 through 12 May 2016 ; 2016 , Pages 113-118 ; 9781467387897 (ISBN) Kamran, D ; Karimian, M ; Nazemipour, A ; Manzuri, M.T ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Knowing the exact position and rotation is a crucial necessity for the navigation of autonomous robots. Even in outdoor environments GPS signals are not always accessible for estimating online rotation and position of robots. Also inertial aided navigation methods have their own defects such as the drift of gyroscope or inaccuracy of accelerometer in agile motions and environmental sensitivity of compass. In this article, we have introduced a novel online visual gyroscope that can estimate the rotation of a moving car with analyzing the images of a monocular camera installed on it. Our real time visual gyroscope utilizes an efficient method of rotation estimation between each pair of camera... 

    Experimental and mathematical analysis of electroformed rotating cone electrode

    , Article Korean Journal of Chemical Engineering ; Volume 37, Issue 4 , April , 2020 , Pages 724-729 ; eISSN: 1975-7220 Heydari, H ; Ahmadipouya, S ; Shoaee Maddah, A ; Rokhforouz, M. R ; Sharif University of Technology
    Springer  2020
    In this study, we present results of a mathematical model in which the governing equations of electroforming process were solved using a robust finite element solver (COMSOL Multiphysics). The effects of different parameters including applied current density, solution electrical conductivity, electrode spacing, and anode height on the copper electroforming process have been investigated. An electroforming experiment using copper electroforming cell was conducted to verify the developed model. The obtained results show that by increasing the applied current density, the electroforming process takes place faster, thereby resulting in a higher thickness of the electroformed layer. In addition,... 

    A robust watermarking method for color images using Naive-Bayes classifier

    , Article Proceedings of the Fifth IASTED International Conference on Signal and Image Processing, Honolulu, HI, 13 August 2003 through 15 August 2003 ; Volume 5 , 2003 , Pages 8-12 ; 0889863784 (ISBN) Yaghmaie, F ; Jamzad, M ; Sharif University of Technology
    By watermarking an image, we hide a pattern in it in such a way that the pattern is not visible but can be extracted using a decomposition algorithm and a key in the receiver side. The watermark pattern can be a character string or any small image (pattern). One of the main applications of watermarking is its application in proving digital image ownership in widely used Internet. In this paper, we present a watermarking method for color images which is robust with respect to usual attacks such as noise addition, smoothing, compression and also rotation. The validity of correctness of retrieved watermark is based on the result of a Naive-Bayes classifier. This classier was trained on a set of... 

    Modeling and qualitative experiments on swirling bubbly flows: Single bubble with rossby number of order 1

    , Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 125, Issue 2 , 2003 , Pages 239-246 ; 00982202 (ISSN) Magaud, F ; Najafi, A. F ; Angilella, J. R ; Souhar, M ; Sharif University of Technology
    The behavior of an isolated bubble in a single-phase swirling flow is investigated theoretically and experimentally. The Rossby number is such that the liquid flow can be approximated by a solid-body rotation superposed to a uniform axial velocity. The equations of the motion of the bubble are solved analytically and numerically, by assuming that the bubble is small and does not modify the water flow. Two kinds of bubbles have been considered: clean bubbles and bubbles with a contaminated interface. In the latter case the bubble is treated as a solid sphere. In both cases a critical angular velocity ωc for the rotating device is found. When ω<ωc the trajectory of the bubble is a conical... 

    Loading and unloading behaviour of a thermoplastic disc

    , Article International Journal of Pressure Vessels and Piping ; Volume 78, Issue 9 , 2001 , Pages 637-645 ; 03080161 (ISSN) Jahed, H ; Shirazi, R ; Sharif University of Technology
    The calculation of loading and residual stresses, and associated strains and displacements, are reported for shrink fitted rotating discs at elevated temperatures. A range of material behaviour is considered including unloading described by an actual material curve, or modelled by isotropic of kinematic hardening with a variable Bauschinger effect. Various collapse loads are obtained and discussed for design boundaries. The influence of reloading on the residual stresses is also studied. It is shown that after the first few loadings of a disc, the residual stress field becomes constant. © 2001 Elsevier Science Ltd. All rights reserved  

    Design and construction of a soccer player robot ARVAND

    , Article 3rd Robot World Cup Soccer Games and Conferences, RoboCup 1999, 27 July 1999 through 6 August 1999 ; Volume 1856 , 2000 , Pages 745-749 ; 03029743 (ISSN); 9783540410430 (ISBN) Jamzad, M ; Foroughnassiraei, A ; Chiniforooshan, E ; Ghorbani, R ; Kazemi, M ; Chitsaz, H ; Mobasser, F ; Sadjad, S. B ; Sony Corporation ; Sharif University of Technology
    Springer Verlag  2000
    Arvand is a robot specially designed and constructed for playing soccer according to RoboCup rules and regulations for the medium size robots. This robot consists of three main parts: mechanics (motion mechanism and kicker), hardware (image acquisition, processing unit and control unit) and software (image processing, wireless communication, motion control and decision making). The motion mechanism is based on a drive unit, a steer unit and a castor wheel. We designed a special control board which uses two microcontrollers to carry out the software system decisions and transfers them to the robot mechanics. The software system written in C++ performs real time image processing and object... 

    A new approach to heat and mass transfer in a rotary dehumidifier: Modeling and simulation

    , Article 2005 ASME Fluids Engineering Division Summer Conference, Houston, TX, 19 June 2005 through 23 June 2005 ; Volume 1 PART B , 2005 , Pages 1049-1054 ; 0791841987 (ISBN); 9780791841983 (ISBN) Esfandiarinia, F ; Van Paassen, D ; Saidi, M. H ; Sharif University of Technology
    In this paper the analytical and simulation modelling of the combined heat and mass transfer processes that occur in a solid desiccant wheel is carried out. Using the numerical method, the performance of an adiabatic rotary dehumidifier is parametrically studied, and the optimal rotational speed is determined by examining the outlet adsorption-side humidity profiles. An approach to compare the solutions for different conditions used in air dehumidifier has been investigated according to the previous published studies. Comparing the simulated results with the published actual values of an experimental work substantiates the validity of model. The model accuracy with respect to the key... 

    A study of gyroscopic effects on stability of high speed milling

    , Article 2005 ASME International Mechanical Engineering Congress and Exposition, IMECE 2005, Orlando, FL, 5 November 2005 through 11 November 2005 ; Volume 16-1 , 2005 , Pages 659-665 ; 0791842231 (ISBN); 9780791842232 (ISBN); 0791842231 (ISBN); 9780791842232 (ISBN) Movahhedy, M. R ; Mosaddegh, P ; Sharif University of Technology
    Dynamic stability of machine tools during operations is dependent on many parameters including the spindle speed. In high and ultra high speed machining, the gyroscopic on the spindle dynamics becomes more pronounced and can affect the borders of stability of the rotating system. In this paper, a finite element based model of spindle, tool holder and cutting tool based on Timoshenko beam theory is used to obtain the dynamic response of the system when gyroscopic terms are included. An iterative scheme is used to update the speed dependent frequency response of the system for obtaining system stability characteristics. It is shown that the gyroscopic effect reduces the critical depth of cut...