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resonance-region
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Widespread chaos in rotation of the secondary asteroid in a binary system
, Article Nonlinear Dynamics ; Volume 81, Issue 4 , September , 2015 , Pages 2031-2042 ; 0924090X (ISSN) ; Assadian, N ; Sharif University of Technology
Kluwer Academic Publishers
2015
Abstract
The chaotic behavior of the secondary asteroid in a system of binary asteroids due to the asphericity and orbital eccentricity is investigated analytically and numerically. The binary asteroids are modeled with a sphere–ellipsoid model, in which the secondary asteroid is ellipsoid. The first-order resonance is studied for different values of asphericity and eccentricity of the secondary asteroid. The results of the Chirikov method are verified by Poincare section which show good agreement between analytical and numerical methods. It is also shown that asphericity and eccentricity affect the size of resonance regions such that beyond the threshold value, the resonance overlapping occurs and...
A modification on performance of MEMS gyroscopes by parametro-harmonic excitation
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010 ; Volume 5 , 2010 , Pages 433-441 ; 9780791849194 (ISBN) ; Salarieh, H ; Vossoughi, G ; Alasty, A ; Sharif University of Technology
Abstract
In this paper, parametric excitation for MEMS gyroscope proposed by Oropeza-Ramos, et al. [1-4] is examined and problems associated with this kind of excitation are shown. It is proved that origin has exponential stability for some sets of parameter values (including those considered in [1-4]). This stability is shown to be global for linearized system and local for the general nonlinear system. Hence, it is concluded that if there would be a periodic orbit, the system has difficulties reaching it. As a solution, a harmonic term to the parametric excitation is added and the new actuation is referred to as parametro-harmonic excitation. It is shown that there are some parameter values for...
Development of a 3-D multigroup program for Dancoff factor calculation
, Article Annals of Nuclear Energy ; Volume 36, Issue 10 , 2009 , Pages 1486-1497 ; 03064549 (ISSN) ; Vosoughi, N ; Sohrabpour, M ; Sharif University of Technology
2009
Abstract
Several parameters, one of which is the Dancoff Factor (DF), are used to calculate the resonance integral (RI) and reduced flux in the resonance region of heterogeneous systems as well as to accurately determine the group constants for criticality calculations. This paper is a report on the development of a program to calculate the DF correction factor using Monte Carlo method and collision probability definition in three-dimensional (3-D) geometries and with multi energy groups. Hence, the DF for any arbitrary arrangement of cylindrical and slab fuel elements is hereby calculated. The fuel elements are monitored and kept at equal levels, though different material compositions and formations...