Sharif University of TechnologyScientia Iranica1026-309826520191001Adaptive dynamic surface control of a flexible-joint robot with parametric uncertainties274927592049210.24200/sci.2018.20492ENC.G. LiCollege of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, ChinaW. CuiCollege of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, ChinaD.D. YanCollege of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, ChinaY. WangCollege of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, ChinaC.M. WangCollege of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, ChinaJournal Article20170108A new kind of adaptive dynamic surface control (DSC) method is proposed to overcome parametric uncertainties of flexible-joint (FJ) robots. These uncertainties of FJ robots are transformed into linear expressions of inertial parameters which are estimated based on the DSC, and the high-order derivatives in DSC are solved by using first-order filter. The adaptation laws of inertial parameters are designed directly to improve the tracking performance according to the Lyapunov stability analysis. Simulation results for a two-link FJ robot show the better tracking accuracy against model parametric uncertainties. The method used does not need aid of Neural Network (NN), and is simpler and calculation faster than the other adaptive methodsSharif University of TechnologyScientia Iranica1026-309826520191001Cooperative control of a gripped load by a team of quadrotors276027692064210.24200/sci.2018.20642ENH. SayyaadiSchool of Mechanical Engineering, Sharif University of Technology, Azadi Avenue, Tehran 11155-9567 IranA. SoltaniSchool of Mechanical Engineering, Sharif University of Technology, Azadi Avenue, Tehran 11155-9567 IranJournal Article20170130<em>In this paper, an output tracking controller is proposed for cooperative transport of a gripped load by a team of quadrotors. The proposed control law requires measurement of only four state variables; position and yaw angle of the system. Moreover, the controller provides rejection of step and ramp external force disturbances. Also, the control basis vectors derived via optimization facilitate real time determination of quadrotors' control inputs. Numerical simulations show effectiveness of the proposed control scheme and its superiority over formerly designed controllers for such systems.</em>Sharif University of TechnologyScientia Iranica1026-309826520191001Natural convection of CNT-water nanofluid in an annular space between confocal elliptic cylinders with constant heat flux on inner wall277027832106910.24200/sci.2018.21069ENT. TayebiEnergy Physics Laboratory, Department of Physics, Faculty of Exact Sciences, Mentouri Brothers Constantine1 University, Constantine, 25000, Algeria. Faculty of Sciences and Technology, Mohamed El Bachir El Ibrahimi University, Bordj Bou Arreridj, El-Anasser, 34030, Algeria.A.J. ChamkhaDepartment of Mechanical Engineering, Prince Mohammad Bin Fahd University, Al-Khobar, 31952, Saudi Arabia.
Prince Sultan Endowment for Energy and Environment, Prince Mohammad Bin Fahd University, Al-Khobar, 31952, Saudi
Arabia.M. DjezzarEnergy Physics Laboratory, Department of Physics, Faculty of Exact Sciences, Mentouri Brothers Constantine1 University, Constantine, 25000, AlgeriaJournal Article20170301In this paper, free convection heat transfer in an annulus between confocal elliptic cylinders filled with CNT-water nanofluid is investigated numerically. The inner cylinder is at constant surface heat flux while the outer wall is isothermally cooled. Equations of continuity, momentum and energy are formulated using the dimensionless form in elliptic coordinates for two-dimensional, laminar and incompressible flow under steady state condition, which is expressed in terms of vorticity and stream function. The governing equations are discretized using the control volume method. For the thermo-physical properties of CNTs, empirical correlations are used in terms of the volume fraction of nanoparticles. For the effective thermal conductivity of CNTs, a new model has been used. The study is performed for modified Rayleigh number (10<sup>3</sup>≤ <em>Ra<sub>m</sub></em> ≤10<sup>6</sup>), volume fraction of nanoparticles (0≤ f ≤0.12). The eccentricity of the inner and outer ellipses and the angle of orientation are fixed at 0.9, 0.6 and 0°, respectively. Results are presented in the form of streamlines, isotherm contours, and distribution of temperature and local and average Nusselt numbers on solid boundaries. The results are also discussed in detail and a very good agreement exists between the present results and those from the literature.Sharif University of TechnologyScientia Iranica1026-309826520191001Cooperative search and localization of ground moving targets by a group of UAVs considering fuel constraint278428042118610.24200/sci.2018.21186ENH. NobahariDepartment of Aerospace Engineering, Sharif University of Technology, Zip Code 1458889694, Tehran, IranM. EffatiِDepartment of Aerospace Engineering, Sharif University of Technology, Zip Code 1458889694, Tehran, IranM. MotieDepartment of Aerospace Engineering, Sharif University of Technology, Zip Code 1458889694, Tehran, IranJournal Article20170313A cooperative task allocation and search algorithm is proposed to find and localize a group of ground based moving targets using a group of Unmanned Air Vehicles (UAVs), working in a decentralized manner. It is assumed that targets have RF emissions. By using an algorithm including Global Search (GS), Approach Target (AT), Locate Target (LT) and Target Reacquisition (TR) modes, UAVs cooperatively search the entire parts of a desired area, approach to the detected targets, locate the targets, and search again to find the targets that stop transmitting their RF emissions during the localization process, respectively. In GS mode, UAVs utilize a cost function to select the best zone for search. In LT mode, each UAV performs a circular motion around the target and uses extended Kalman filter to estimate the target position. Furthermore, a fuel tanker is considered to provide fuel for UAVs during the flight. Therefore, two more operating modes as Approach to Fuel Tanker (AFT) and Fueling (FUE) are added to the operating modes. Before switching to the AFT mode, UAVs take turn using a fueling decision function. In AFT mode, the future position of the fuel tanker is predicted by UAVs to reduce the approach time.Sharif University of TechnologyScientia Iranica1026-309826520191001Influence of tool material on forces, temperature, and surface quality of Ti-15333 alloy in CT and UAT280528162069210.24200/sci.2018.20692ENR. MuhammadDepartment of Mechanical Engineering, CECOS University of IT & Emerging Sciences, Peshawar, KPK, PakistanN. AhmedDepartment of Mechanical Engineering, CECOS University of IT & Emerging Sciences, Peshawar, KPK, PakistanS. MaqsoodFaculty Of Industrial Engineering, UET Peshawar Jalozai Campus, PakistanK. AlamDepartment of Mechanical and Industrial Engineering, Sultan Qaboos University, Musqat, OmanM.U. RehmanDepartment of Mechanical Engineering, CECOS University of IT & Emerging Sciences, Peshawar, KPK, PakistanV. V. SilberschmidtWolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, UKJournal Article20170501<em>Ultrasonically assisted turning (UAT)</em> is a progressive machining method in which vibration is applied to the cutting insert in the direction of the cutting tool velocity to reduce the cutting forces, significantly and increase the surface finish noticeably. However, the key question about the tool damage caused by the vibration and its effect on the cutting forces, surface roughness and process zone temperature is still unknown in UAT.<br />This paper presents experimental analysis of the effect of worn tool in UAT and conventional-turning (CT) of β-Ti-15V-3Al-3Cr-3Sn (Ti-15333) alloy on surface quality of a machined surface, temperature of the process zone and cutting forces using KC5510 (PVD TiAlN) and CP500 (PVD (Ti,Al)N-TiN) cutting inserts. In UAT, the tool edge damages in CP500 inserts increased with tested machining time resulted a growth of 8 N and 10 N in tangential force component in CT and UAT, respectively. Similarly, with the progression of tool edge damage, a growth of 1.7% and 9.3% in process zone temperature was observed in CT and UAT, respectively. The surface roughness results revealed a gradual degradation with machining time, however, the results UAT with a worn tool was significantly better when compared to CT, with a virgin tool.Sharif University of TechnologyScientia Iranica1026-309826520191001Soret and Dufour effects on doubly diffusive convection of nanofluid over a wedge in the presence of thermal radiation and suction281728262099710.24200/sci.2018.20997ENR.Md. KasmaniCentre for Foundation Studies in Science, University of Malaya, Kuala Lumpur 50603, MalaysiaS. SivasankaranDepartment of Mathematics, King Abdulaziz University, Jeddah 21589, Saudi ArabiaM. BhuvaneswariDepartment of Mathematics, King Abdulaziz University, Jeddah 21589, Saudi ArabiaA.S. AlshomraniDepartment of Mathematics, King Abdulaziz University, Jeddah 21589, Saudi ArabiaZ. SiriInstitute of Mathematical Sciences, University of Malaya, Kuala Lumpur 50603, MalaysiaJournal Article20170521This paper is devoted to investigate the influences of thermal radiation, Dufour and Soret effects on doubly diffusive convective heat transfer of nanoliquid over a wedge in the presence of wall suction. The governing equations are transformed to nonlinear ordinary differential equations using similarity transformation. The resulting system is solved numerically using fourth-order Runge-Kutta-Gill method with shooting technique and Newton-Raphson method. The solutions are expressed in terms of velocity, temperature, solutal concentration and volume fraction profiles. The effects of pertinent parameters entering into the problem such as wedge angle, thermal radiation, Brownian motion, thermophoresis, Soret and Dufour numbers on the skin friction coefficient, local Nusselt number and local Sherwood number are discussed in detail.Sharif University of TechnologyScientia Iranica1026-309826520191001Dynamic adaptive mesh refinement of Fluid-structure interaction using immersed boundary method with two-stage corrections282728382073810.24200/sci.2018.50347.1650ENM.S. AldlemyDepartment of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia. Department of Mechanical Engineering, Collage of Mechanical Engineering Technology, Benghazi-Libya.M.R. RasaniDepartment of Mechanical and Materials Engineering, Faculty of Engineering and
Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, MalaysiaT.M.Y.S. TuanDepartment of Mechanical Engineering, Faculty of Engineering, Universiti Teknologi Petronas, 31750 Tronoh, Perak, MalaysiaA.K. AriffinDepartment of Mechanical and Materials Engineering, Faculty of Engineering and
Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, MalaysiaJournal Article20180126The application of the immersed boundary method (IBM) coupled with adaptive mesh refinement (AMR) is considered one of the powerful tools for solving complex viscous incompressible flow problems. In this paper, the IBM was combined with AMR to solve complex incompressible and viscous fluid with elastic and rigid body problems concerning large structural deformations. In the IBM, the solid and fluid motions at the interface are united by a body force which can be compared to a fraction of a solid volume. The work aims to develop an automatic adaptive mesh refinement strategy to improve the solution near the fluid-structure interface. This is necessary as the flow field might be significantly affected by the structure; therefore, it was essential to precisely capture the boundary layers. The computational results highlighted the capability of this method to improve the flow resolution near the fluid structure. The proposed approach is validated using 2D numerical examples. The approach is validated in terms of its superior performance. The combined IBM-Adaptive mesh refinement approach showed a promising outcome for the investigated mechanical problem. The performance of the method in achieving a solution within a reasonably low computation time is also commendable.Sharif University of TechnologyScientia Iranica1026-309826520191001High-performance controller design and evaluation for active vibration control in boring283928532073110.24200/sci.2018.50411.1684ENP. Naeemi AminiDepartment of Mechanical Engineering, Ferdowsi University of Mashhad (FUM), Mashhad, P.O. Box 9177948974, Iran.B. Moetakef-ImaniDepartment of Mechanical Engineering, Ferdowsi University of Mashhad (FUM), Mashhad, P.O. Box 9177948974, Iran.0000-0002-0852-4621Journal Article20180207High quality manufactured components with fast production rate is an increasing demand of modern machine tool industry. Internal machining operations due to the large length to diameter ratio are most prone to intolerable chatter vibrations and proved to be an extremely challenging process. This paper presents a new method for proper design of direct velocity feedback (DVF) controller in order to extend boundaries of stable cutting for internal turning with minimum control effort. Control effort and active damping performance are two counteracting parameters that affect the results of active vibration control. After properly implementing the DVF active control algorithm on the internal turning setup, stable boundaries for different control gains of DVF controller are thoroughly studied. The comparison shows that although high DVF gains may considerably improve dynamic stiffness of the tool, it leads to the maximum control effort and actuator saturation and consequently process instability. The proposed gain selection method results in a significant increase in stable machining over the desired range of cutting conditions. The suggested design approach of the DVF controller can considerably improve limitations of rough machining on long over hang boring bars.Sharif University of TechnologyScientia Iranica1026-309826520191001Dynamic behavior of worn wheels in a track containing several sharp curves based on Field data measurements and simulation285428642060110.24200/sci.2018.50749.1849ENS. M. SalehiSchool of Mechanical Engineering, Sharif University of Technology, Tehran, IranG. H. FarrahiSchool of Mechanical Engineering, Sharif University of Technology, Tehran, IranS. SohrabpourSchool of Mechanical Engineering, Sharif University of Technology, Tehran, IranJournal Article20180408Study of the wheel and rail wear phenomenon can provide the optimal use of wheel profile which results cost efficiency, dynamic stability, travel comfort, and safety to prevent the derailment especially in curves. In this paper, the experimental data is recorded in the from the field measurements worn wheels of a passenger wagon in the “Southern line” of Iran’s railway system and is combined with the dynamic simulations to study the effects of severe wheel flange wear on the dynamics of wagon. The results show that the amount of wheel wear (especially the wheel flange) directly impacts the dynamic behavior of the wagon in curves. In addition, based on the history of wear index and the peak derailment ratio, the appropriate range of the wheel flange thickness in order to repair or replace the worn wheels is suggested in the range of 25 to 27 mm.Sharif University of TechnologyScientia Iranica1026-309826520191001Mathematical modeling of thermal contact resistance for different curvature contacting geometries using a robust approach286528712073910.24200/sci.2018.50771.1856ENM.H. ShojaeefardSchool of Mechanical Engineering, Iran University of Science and Technology, Tehran, P.O. Box 16765-163, Iran.K. Tafazzoli AghvamiSchool of Mechanical Engineering, Iran University of Science and Technology, Tehran, P.O. Box 16765-163, Iran.Journal Article20180417Nowadays having deep knowledge on thermal contact conductance (TCC) and thermal conduct resistance (TCR) existed between various type metals is interesting during heat transfer occurrence in the nuclear reactor, thermal control system of spacecraft, and heat exchangers. In this present contribution, artificial neural network (ANN) coupled with multi-layer perceptron (MLP) modeling was utilized for the prediction of transient temperature contour in various contacting surface such as flat-flat, flat-cylinder, cylinder-cylinder. In order to develop accurate transient model, position, time, and roughness parameter of metal was used as input parameter and temperature of solid bodies decided as target parameter of model. Modeling results indicates that ANN base modeling show great accuracy in comparison with other numerical methods. Also, values of average absolute relative deviation (AARD), coefficient of determination (R2) for the overall data is 0.056 and 0.996 respectively which clarifies the accuracy and robustness of the proposed model.Sharif University of TechnologyScientia Iranica1026-309826520191001Numerical simulation of a novel Trombe wall-assisted desiccant wheel287228832124610.24200/sci.2019.52042.2502ENM. BahramkhooFaculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, P.O. Box
14515/775, Iran.K JavaherdehFaculty of Mechanical Engineering, University of Guilan, Rasht, P. Code 4199613776, Iran.F. AtabiFaculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, P.O. Box
14515/775, IranA. EmamzadehDepartment of Petroleum and Chemical Engineering, Science and Research Branch, Islamic Azad University, Tehran, P.O. Box
14515/775, Iran.Journal Article20181017In the present study, a novel trombe wall-assisted desiccant wheel system has been modeled, in which the trombe wall is divided into three equal parts and it provides the heat energy needed to regenerate the desiccant wheel. The components of the system, including the desiccant wheel, the trombe wall are separately modeled in MATLAB software and then assembled to investigate the surface area of the trombe wall and the output humidity of the desiccant wheel for attaining air conditioning comfort. It has been discussed that the integrated system presented here, can be utilized in all humid climate conditions around the globe. The results of the present study for some special cases have been compared with results available in open literature. The optimal surface area of the trombe wall has been extracted according to the parameters of the desiccant wheel. Results shows that the solar energy received by the trombe wall is 600-740 W/m2 (1May – 15August) in warm and humid climate of Gilan (Iran), the temperature of the wall surface is obtained 77-86 ºC, and the outlet temperature of regeneration air stream from trombe wall is obtained 60-70 ºC, the output humidity of the desiccant wheel reduces 10-12 gw/kga.