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rotational-dynamics
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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) ; Assadian, N ; Sharif University of Technology
Academic Press Inc
Abstract
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...
Nonlinear observer design for turbocharger in a SI engine
, Article Proceedings of the American Control Conference ; 2013 , pp. 5231-5236 ; ISSN: 07431619 ; ISBN: 9781479901777 ; Shahbakhti, M ; Alasty, A ; Vossoughi, G. R ; Sharif University of Technology
Abstract
Estimation of major turbocharger variables is essential for proper control and monitoring of a turbocharged engine. This work presents a novel algorithm to estimate turbocharger rotator speed, air temperature downstream a compressor and flow rate over the compressor using mean value models of engine subsystems. A nonlinear Luenberger observer is designed for a 1.7-lit gasoline turbocharged engine. The designed observed is shown analytically to be asymptotically stable. Performance of the designed observer is experimentally validated with the data collected from the engine. The results indicate the observer can capture major turbocharger's rotational dynamics and estimated turbocharger...
Nonlinear observer design for turbocharger in a SI engine
, Article Proceedings of the American Control Conference ; 2013 , Pages 5231-5236 ; 07431619 (ISSN) ; 9781479901777 (ISBN) ; Shahbakhti, M ; Alasty, A ; Vossoughi, G. R ; Sharif University of Technology
2013
Abstract
Estimation of major turbocharger variables is essential for proper control and monitoring of a turbocharged engine. This work presents a novel algorithm to estimate turbocharger rotator speed, air temperature downstream a compressor and flow rate over the compressor using mean value models of engine subsystems. A nonlinear Luenberger observer is designed for a 1.7-lit gasoline turbocharged engine. The designed observed is shown analytically to be asymptotically stable. Performance of the designed observer is experimentally validated with the data collected from the engine. The results indicate the observer can capture major turbocharger's rotational dynamics and estimated turbocharger...
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...
Motion of a hexagonal pencil on an inclined plane
, Article American Journal of Physics ; Volume 77, Issue 5 , 2009 , Pages 401-406 ; 00029505 (ISSN) ; Sharif University of Technology
2009
Abstract
This article discusses a hexagonal prism rolling down an inclined plane, which is easy to realize experimentally and yields results that are consistent with a simple theory. This investigation would make an excellent undergraduate project. © 2009 American Association of Physics Teachers
Role of graphene surface ripples and thermal vibrations in molecular dynamics of C60
, Article Journal of Physical Chemistry C ; Volume 123, Issue 32 , 2019 , Pages 20026-20036 ; 19327447 (ISSN) ; Nejat Pishkenari, H ; Ejtehadi, M. R ; Akimov, A. V ; Sharif University of Technology
American Chemical Society
2019
Abstract
Nanocars are artificial molecular machines with chassis, axles, and wheels designed for nanoscale transport at materials' surfaces. Understanding the dependence of surface dynamics of nanocars on the substrate's physicochemical properties is critical to the design of the transport properties of such man-made nanoscale devices. Among the multitude of potential substrates for the nanotransporters, graphene exhibits intrinsic ripples on its surface, which may affect the surface dynamics of nanocars. In this work, we report our molecular dynamics study of motion of C60, a popular nanocar wheel, on the graphitic substrates with systematically controllable surface ripples. We find that surface...
Translational and Rotational Dynamics and Control Of an All-Thruster Satellite Considering Fuel Slosh
, M.Sc. Thesis Sharif University of Technology ; Assadian, Nima (Supervisor)
Abstract
The purpose of the present study is to model and control a 6DOF satellite dynamics with a rigid body in the Earth’s orbit including the fuel slosh. The satellite manages and controls its attitude and position by twelve ON-OFF thrusters installed alongside the principal body axes. Moreover, due to using the liquid fuel to feed these thrusters, fuel slosh may have a strong dynamical effect on the satellite translational and rotational dynamics and control. The thrusters’ activation may result in fuel slosh and the impact of their frequent switching ON-OFF on fuel is considered in this study. The thrusters force magnitude, switching intervals, and their frequencies can affect the magnitude of...
Increasing Robustness and Performance of the Ins-Dvl Underwater Navigation by Using Model-Aided Navigation
, Ph.D. Dissertation Sharif University of Technology ; Salarieh, Hassan (Supervisor) ; Alasty, Aria (Supervisor) ; Hashemi, Mojtaba (Co-Supervisor)
Abstract
Dopller velocity log (DVL) is an important underwater navigation sensor. But in the INS-DVL integrated navigation systems, positional error grows unlimitedly over time. Also, the losing bottom lock (LBL) phenomenon is possible in DVL for various reasons such as AUV severe angular changes. So INS-DVL systems are not robust against environmental disturbances resulting in LBL. In this research, mode-aided navigation is used to improve the INS-DVL navigation system. Model-aided navigation is divided into two categories: using kinematic constraints and using kinetic model. Both approaches are used in this research to improve navigation performance and robustness. Initially, the existing kinematic...
Sliding Mode Observers to Detect and Isolate Faults in a Turbocharged Gasoline Engine
, Article SAE International Journal of Engines ; Volume 8, Issue 2 , April , 2015 , Pages 399-410 ; 19463936 (ISSN) ; Alasty, A ; Vossoughi, G. R ; Sharif University of Technology
SAE International
2015
Abstract
This paper presents a novel model-based algorithm which is able to detect and isolate major faults assigned to the gas exchange path of a gasoline engine both in the intake and exhaust sides. The diagnostics system is developed for detection and isolation of these faults: air leakage fault between the compressor and the air throttle, exhaust manifold pressure sensor fault, wastegate stuck-closed fault and wastegate stuck-open fault. Sliding mode observers (SMOs) are the core detection algorithms utilized in this work. A first order SMO is designed to estimate the turbocharger rotational dynamics. The wastegate displacement dynamics coupled to the exhaust manifold pressure dynamics is...
Universal rotation of nanowires in static uniform electric fields in viscous dielectric liquids
, Article Applied Physics Letters ; Volume 113, Issue 6 , 2018 ; 00036951 (ISSN) ; Esfandiar, A ; Moshfegh, A. Z ; Sharif University of Technology
American Institute of Physics Inc
2018
Abstract
The wide utilization of nanomanipulation as a promising approach in microorganisms, nanoelectromechanical systems, and assembly of nanostructures remarks the importance of nanostructures' motion in electric fields. Here, we study the rotational dynamics of metallic and non-metallic nanowires (NWs) in a static uniform electric field in viscous dielectric liquids. For metallic NWs, it has been theoretically shown that the electric field-induced rotation is practically independent of the geometrical dimensions and the electrical properties of NWs. Our experimental results for suspended silver (Ag) NWs in microscope oil are perfectly in agreement with this model. However, in the case of TiO2...
Optimal controller design for 3D manipulation of buoyant magnetic microrobots via constrained linear quadratic regulation approach
, Article Journal of Micro-Bio Robotics ; Volume 15, Issue 2 , 2019 , Pages 105-117 ; 21946418 (ISSN) ; Nejat Pishkenari, H ; Sitti, M ; Sharif University of Technology
Springer
2019
Abstract
We consider magnetic actuation and control of a spherical neutrally buoyant magnetic microrobot via magnetic coil setups and seek to design an optimal controller to reduce the required energy and coils’ currents. We showed that in currently employed setups, where the actuation frequency is few tens of Hertz, the nonlinear dynamics of the system can be well approximated by a set of linear constrained ones. The approximated model is obtained by consciously overlooking the rotational dynamics and the inertia terms in translational dynamics. We acquired the linear quadratic regulation (LQR) controller for the approximated model which is a constrained time-varying system. Finally, 3D manipulation...
Analysis and Increase Robustness of INS-DVL Navigation Using Rotational Model of AUV in the Presence of Model Uncertainty
, M.Sc. Thesis Sharif University of Technology ; Alasti, Aria (Supervisor) ; Salarieh, Hasaan (Supervisor) ; Hashemi, Mojtaba (Co-Supervisor)
Abstract
Autonomous underwater vehicle are among the subsurface vehicles used today in applications such as ocean floor mapping, environmental studies, finding the wreckage of drowned vehicles, and military applications such as finding mines. The need for control over the navigation components and the importance of the precise position of the mission have made AUV navigation an important issue in these vehicles. Due to the attenuation of the GPS signal underwater, it is not possible to use this method for subsurface navigation. Therefore, inertial navigation (dead reckoning navigation) is usually used for this purpose. Due to the unlimited growth of inertial sensor error over time, this error must be...
INS-DVL navigation improvement using rotational motion dynamic model of AUV
, Article IEEE Sensors Journal ; Volume 20, Issue 23 , 2020 , Pages 14329-14336 ; Hashemi, M ; Salarieh, H ; Alasty, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
INS-DVL integration is a common method for underwater navigation. However, inherent errors of sensors, especially in MEMS IMUs, lead to inaccuracies in estimating the position and attitude. In this paper, dynamic motion model of AUV is used to improve MEMS INS-DVL navigation. In this method, which is called model-aided or model-based navigation, the information of the kinetic model of the vehicle (obtained from Newton-Euler equations) is used to improve the navigation performance. Previous model-aided navigation studies about AUVs have been focused on the translational dynamic model of vehicles. As the best of our knowledge, this paper is the first one which suggests using a rotational...