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mechanical-engineering
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Designing gear-shift pattern for an electric vehicle to optimize energy consumption
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Vol. 11 , 2010 , pp. 837-846 ; ISBN: 9780791844489 ; Salehi, R ; Alasty, A ; Sharif University of Technology
Abstract
In this paper optimization of energy consumption in an electric vehicle is presented. The main idea of this optimization is based on selecting the best gear level in driving the vehicle. Two algorithms for optimization are introduced which are based on fuzzy rules and fuzzy controllers. In first algorithm, fuzzy controller simulates energy consumption in different gear levels, and chooses the optimum gear level. While in second method, fuzzy controller detects the optimum gear level by measuring the vehicle's average speed and acceleration. To investigate the performance of these controllers, a model of TOSAN vehicle is developed and the controllers outputs are checked in simulation of TOSAN...
Stabilizing periodic orbits of the fractional order chaotic van der pol system
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Vol. 8, Issue PARTS A AND B , 2010 , pp. 175-183 ; ISBN: 9780791844458 ; Salarieh, H ; Alasty, A ; Sharif University of Technology
Abstract
In tins paper, stabilizing the unstable periodic orbits (UPO) in a chaotic fractional order system called Van der Pol is studied. Firstly, a technique for finding unstable periodic orbit in chaotic fractional order systems is stated. Then by applying tins technique to the van der Pol system, unstable periodic orbit of system is found. After that, a method is presented for stabilization of the discovered UPO based on theories stability of the linear integer order and fractional order systems. Finally, a linear feedback controller was applied to the system and simulation is done for demonstration of controller performance
Performance control of a tape transport mechanism using entire eigenstructure assignment
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings ; Vol. 10, Issue PART A , 2010 , pp. 133-140 ; ISBN: 9780791843833 ; Hajikolaei, K. H ; Motamedi, M ; Alasty, A ; Sharif University of Technology
Abstract
To achieve high rate of data transfer, tape mechanisms must be able to transport the tape with a constant velocity for scanning. During this process, it is desired to make the rise time minimized without timing and data transfer errors. In this paper, three servo systems including the take-up and supply reel servos for tape tension control and capstan servo for speed control are considered. So, tape transport mechanisms can be described with a nonlinear multi-input multi-output system (MIMO). After state-space representation of the problem, feedback control is designed for tracking objective. It should be mentioned that an increase in the speed of time response of system corresponds to an...
Equations of motion of a ring-like robot with a flexible body and creeping-rolling motion
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings ; 2010 , pp. 191-197 ; ISBN: 9780791843833 ; Alasty, A ; Sharif University of Technology
Abstract
The robots that can move on rough terrains are very important especially in Rescue operation, exploration, etc. In this research, a mechanism is introduced for a ring-like robot with a flexible body. This robot is moved by arms which are placed radially and have Reciprocating motion in this direction. By controlling the contraction and the extension of the arms which contact lhe ground, the robot will be forced to move which is called rolling-creeping motion. The robot is stable in stationary state.; also the maximum angle which it can be stable is determined. Considering the speed of contracted arm is the input parameter, the speed of the extended arm for locomotion of the robot has been...
Optimal sliding mode control of AFM tip vibration and position during manipulation of a nanoparticle
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings ; Vol. 12, Issue. PART A , 2010 , pp. 205-214 ; ISBN: 9780791843857 ; Khorsand, M ; Meghdari, A ; Alasty, A ; Sharif University of Technology
Abstract
This research regards to a two-dimensional lateral pushing nanomanipulation using Atomic Force Microscope (AFM). Yet a reliable control of the AFM tip position during the AFM-based manipulation process is a chief issue since the tip can jump over the target nanoparticle and then the process can fail. However, a detailed Modeling and understanding of the interaction forces on the AFM tip is important for prosperous manipulation control and a nanometer resolution tip positioning. In the proposed model, Lund-Grenoble (LuGre) dynamic friction model is used as friction force on the contact surface between the nanoparticle and the substrate. This model leads to a stick-slip behavior of the...
Non-equilibrium model of gravity drainage in a single block
, Article Journal of Porous Media ; Vol. 16, issue. 6 , 2013 , p. 559-571 ; ISSN: 1091028X ; Ghazanfari, M. H ; Masihi, M ; Sharif University of Technology
Abstract
This work concerns with developing a non-equilibrium model of gravity drainage in a single block. The proposed model which considers both non-equilibrium effects of capillary pressure and relative permeabilities is used for prediction of oil recovery by gravity drainage from a single block. Close agreement observed between the model results and experimental data disclosed that the non-equilibrium assumption is completely reliable for modeling of gravity drainage. The results revealed that when the characteristic time of the saturation variation is comparable with the time required to establish capillary equilibrium, the non-equilibrium effects in gravity drainage must be considered. The...
Polysilicon nano-beam model based on modified couple stress and Eringen's nonlocal elasticity theories
, Article Physica E: Low-Dimensional Systems and Nanostructures ; Vol. 63, issue , 2014 , p. 223-228 ; Pishkenari, H. N ; Yousefi-Koma, A ; Hoorzad, H ; Sharif University of Technology
Abstract
In recent years, extensive experiments have shown that classical continuum theory cannot predict the behavior of mechanical microstructures with small size. To accurately design and analyze micro- and nano-electro-mechanical systems, size-dependent continuum theories should be used. These theories model micro- and nano-electro-mechanical systems with higher accuracy because they include size-dependent parameters. In this paper, polysilicon nano-beam is modeled using modified couple stress and Eringen's nonlocal elasticity theories. First, partial differential equations governing the vibration of nano-beams are converted to a one D.O.F. differential equations using Galerkin method, resulting...
Characterization of the effect of disturbance on the hydro-mechanical behavior of a highly collapsible loessial soil
, Article Unsaturated Soils: Research and Applications - Proceedings of the 6th International Conference on Unsaturated Soils, UNSAT 2014 ; Vol. 1, issue , 2014 , p. 261-266 ; Khosravi, A ; Ghaizadeh, S ; Garakani, A. A ; Meehan, C. L ; Sharif University of Technology
Abstract
Highly collapsible loessial soils are characterized by an open void structure that can experience significant settlement upon loading. In the field, these partially saturated Aeolian deposits are particularly susceptible to wetting-induced collapse. Due to difficulties in preparing undisturbed specimens from highly collapsible soils, previous studies have generally performed laboratory tests on reconstituted specimens with different water contents and densities, and the effect of disturbance on the initial state of the soil was ignored. Disturbance in highly collapsible soil specimens may significantly affect the natural composition of the soil matrix, the non-homogeneous distribution of...
Nonlinear dynamic modeling and simulation of an insect-like flapping wing
, Article Applied Mechanics and Materials ; Vol. 555, issue , 2014 , p. 3-10 ; Taymourtash, N ; Sharif University of Technology
Abstract
The main objective of this paper is to present the modeling and simulation of open loop dynamics of a rigid body insect-like flapping wing. The most important aerodynamic mechanisms that explain the nature of the flapping flight, including added mass, rotational lift and delayed stall, are modeled. Wing flapping kinematics is described using appropriate reference frames and three degree of freedom for each wing with respect to the insect body. In order to simulate nonlinear differential equations of motion, 6DOF model of the insect-like flapping wing is developed, followed by an evaluation of the simulation results in hover condition
Toward searching possible oscillatory region in order space for nonlinear fractional-order systems
, Article Journal of Computational and Nonlinear Dynamics ; Vol. 9, issue. 2 , 2014 ; Sharif University of Technology
Abstract
Finding the oscillatory region in the order space is one of the most challenging problems in nonlinear fractional-order systems. This paper proposes a method to find the possible oscillatory region in the order space for a nonlinear fractional-order system. The effectiveness of the proposed method in finding the oscillatory region and special order sets placed in its boundary is confirmed by presenting some examples
Investigation of the mechanical behaviors of carbon nanotubes under electrostatic actuation using the modified couple stress theory
, Article Fullerenes Nanotubes and Carbon Nanostructures ; Volume 21, Issue 10 , Oct , 2013 , Pages 930-945 ; 1536383X (ISSN) ; Rastgoo, A ; Ahmadian, M. T ; Sharif University of Technology
2013
Abstract
The paper presents size-dependant mechanical behaviors of carbon nanotubes under electrostatic actuation using modified couple stress theory. The behaviors of the carbon nanotubes with different geometries and boundary conditions are studied in detail. The results reveal that application of this theory results in higher pull-in voltages for both cantilever and doubly clamped boundary conditions
The hydro-mechanical behavior of infilled rock joints with fill materials in unsaturated conditions
, Article Geotechnical Special Publication ; Issue 231 , 3-7 March , 2013 , Pages 129-138 ; 08950563 (ISSN) ; 9780784412787 (ISBN) ; Khosravi, M ; Meehan, C. L ; Sharif University of Technology
2013
Abstract
The existence, nature, and frequency of discontinuities in a given rock mass typically govern the overall shear behavior of the rock. The presence of fine materials such as clay and silt within rock joints, whether the product of infilling or natural weathering processes, can have a significant effect on the shear behavior of the rock joint. When assessing the strength of filled rock joints, it is therefore necessary to determine the separate strengths of both the rock and the joint infill material, and to also have a good understanding of the interaction between the two for various joint geometries and levels of infilling. Much of the existing research on the shear strength of filled rock...
How to synchronize and register an optical-inertial tracking system
, Article Applied Mechanics and Materials ; Volume 332 , 2013 , Pages 130-136 ; 16609336 (ISSN) ; 9783037857335 (ISBN) ; Akbar, M ; Farahmand, F ; Sharif University of Technology
2013
Abstract
Multi-sensor tracking is widely used for augmentation of tracking accuracy using data fusion. A basic requirement for such applications is the real time temporal synchronization and spatial registration of two sensory data. In this study a new method for time and space coordination of two tracking sensor measurements has been presented. For spatial registration we used a body coordinate system and then applied the effect of the level arm. The time synchronization was done based on least mean square (LMS) error method. This method was implemented to synchronize the position and orientation of an object using Inertial (1IMU) and Optical (Optotrak) tracking systems. The results of synchronized...
Multi-objective genetic algorithm for hover stabilization of an insect-like flapping wing
, Article Applied Mechanics and Materials ; Volume 332 , 2013 , Pages 50-55 ; 16609336 (ISSN) ; 9783037857335 (ISBN) ; Banazadeh, A ; Sharif University of Technology
2013
Abstract
This paper describes latest results obtained on modeling, simulation and controller design of an insect-like Flapping Wing Micro Air Vehicle (FWMAV). Because of the highly nonlinear and time varying nature of insect flight and the inability to find an equilibrium point, linearization of the model without compromising the accuracy is not possible. Therefore, to address the problem of designing a controller capable of stabilizing and controlling the FWMAV around a hovering point, a metaheuristic optimization approach is proposed, based on the time averaging theorem. The results show that a controller, designed using the proposed method, is capable of stabilizing the FWMAV effectively around...
Design methodology and preliminary sizing of an unmanned mars exploration plane (UMEP)
, Article APPLIED MECHANICS AND MATERIALS; 332; 15; Biomechanics, neurorehabilitation, mechanical engineering, manufacturing systems, robotics and aerospace: optimization of the engineering systems; OPTIROB 2013 ; Volume 332 , 2013 , Pages 15-20 ; 16609336 (ISSN) ; 9783037857335 (ISBN) ; Banazadeh, A ; Golkhandan, A. R ; Sharif University of Technology
2013
Abstract
This paper discusses the mission requirements and design constraints for an Unmanned Martian research aircraft based on a tailor-made classical airplane design methodology. First, the exploration mission is described using the information from previous real-world experiences and the desired payload is proposed accordingly. The environmental conditions that dictate severe constraints to the design space are characterized afterwards. The conventional airplane design cycle is modified to address the lack of statistical data and to define a proper design recycling criteria. Eventually, the outcome is presented in the form of a novel configuration that is well suited to carry out the specified...
Frequency response analysis for dynamic model identification and control of a ducted fan aerial vehicle in hover
, Article Applied Mechanics and Materials, Neptun-Olimp ; Volume 332 , 2013 , Pages 56-61 ; 16609336 (ISSN) ; 9783037857335 (ISBN) ; Banazadeh, A ; Sharif University of Technology
2013
Abstract
System Identification is a key technology for the development and integration of modern engineering systems including unconventional flying vehicles. These systems are highly parametric with complex dynamics and nonlinearities. Ducted fans are special class of these vehicles that can take off vertically, hover and cruise at very low speed. In this paper, an exact equivalent linear system is found from the non-linear dynamic model of a ducted fan by use of frequency response identification. Here, power spectral density analysis is performed, using CIFER software, to evaluate the input-output responses in hover and to derive the transfer functions based on the coherence criterion. Then,...
Non-equilibrium model of gravity drainage in a single block
, Article Journal of Porous Media ; Volume 16, Issue 6 , 2013 , Pages 559-571 ; 1091028X (ISSN) ; Ghazanfari, M. H ; Masihi, M ; Sharif University of Technology
2013
Abstract
This work concerns with developing a non-equilibrium model of gravity drainage in a single block. The proposed model which considers both non-equilibrium effects of capillary pressure and relative permeabilities is used for prediction of oil recovery by gravity drainage from a single block. Close agreement observed between the model results and experimental data disclosed that the non-equilibrium assumption is completely reliable for modeling of gravity drainage. The results revealed that when the characteristic time of the saturation variation is comparable with the time required to establish capillary equilibrium, the non-equilibrium effects in gravity drainage must be considered. The...
Operation of an opto-mechanical system using a double-cell design for liquid color recognition
, Article Optics and Lasers in Engineering ; Volume 51, Issue 7 , July , 2013 , Pages 848-855 ; 01438166 (ISSN) ; Sharif University of Technology
2013
Abstract
Design and operation of an opto-mechanical system employing a double-cell is reported here for the color liquid reflection studies. The reported system consists of a double-fiber optical design and an electro-mechanical scanning system. In this arrangement one fiber transmits the source light to the object surface and the second one transmits the light reflected from the sample to a photodetector. By scanning the double-fiber assembly in one-direction reflection properties of different color liquids are investigated. Reflection signals depend on the cell surface structure and the cell filled material. Two sets of flat/cylindrical cells made of almost similar glass materials are used for this...
Longitudinal behavior of strain gradient bars
, Article International Journal of Engineering Science ; Volume 66-67 , May , 2013 , Pages 44-59 ; 00207225 (ISSN) ; Asghari, M ; Ahmadian, M. T ; Sharif University of Technology
2013
Abstract
In this paper, the strain gradient theory, a non-classical continuum theory capable of capturing the size effect observed in micro-scale structures, is employed in order to investigate the size-dependent mechanical behavior of microbars. For a strain gradient bar, the governing equation of motion and classical and non-classical boundary conditions are derived using Hamilton's principle. Closed form solutions have been analytically obtained for static deformation, natural frequencies and mode shapes of strain gradient bars. The static deformation and natural frequencies of a clamped-clamped microbar subjected to a uniform axial distributed force are derived analytically and the results are...
Static and dynamic analysis of a clamp-clamp nano-beam under electrostatic actuation and detection considering intermolecular forces
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Volume 10 , 2013 ; 9780791856390 (ISBN) ; Barari, A ; Firoozbakhsh, K ; Ahmadian, M. T ; ASME ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2013
Abstract
Micro/nano gyroscopes which can measure angular rate or angle are types of merging gyroscope technology with MEMS/NEMS technology. They have extensively used in many fields of engineering, such as automotive, aerospace, robotics and consumer electronics. There are many studies of a variety of gyroscopes with various drive and detect methods and different resonator structures in last years. In case of electrostatically actuated and detected beam micro/nano-gyroscopes, DC voltages are applied in driving and sensing directions and AC voltage is utilized in driving direction in order to excite drive oscillation. The intermolecular surface forces are especially significant when the gyroscopes are...