2018-06-21T20:47:03Z
http://scientiairanica.sharif.edu/?_action=export&rf=summon&issue=316
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2015
22
5
Multi-Objective Optimization of Truss Structures Using Bees Algorithm
A.
Moradi
A.
Mirzakhani Nafchi
A.
Ghanbarzadeh
this paper wants to apply a multi-objective optimization method for optimizing truss design problem. This method is named as Multi-Objectives Bees Algorithm (MOBA). In the first problem, objective functions are minimizing stress in the two members and minimizing volume of truss , and on each of other three problems, the objectives which should be optimized are value of total weight of structure and also total displacement of nodes with considering limits on cross section of elements. The bees algorithm is developed based on principle of multi-objective problems. A clustering algorithm is applied for multi-objective bees algorithm in order to manage the size of the Pareto-optimal set. The results are good evidence for robustness and effectiveness of multi-objective bees algorithm in solving multi-objective optimal truss design.
Bees Algorithm (BA)
Multi-objective
Optimization
Pareto
Truss Design
2015
10
01
1789
1800
http://scientiairanica.sharif.edu/article_3742_2082e7588e6195845d707b07287214b6.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2015
22
5
Thermo-mechanical Analysis of Functionally Graded Thick Spheres with Linearly Time-dependent Temperature
Ammar
Bayat
Hasan
Moosavi
Yahya
Bayat
The analysis of unsteady-state thermo-mechanical problem of functionally graded thick-walled spheres is presented in this paper. The material properties, except Poisson’s ratio, are assumed to be an arbitrary function of radial direction. Considering linearly increasing boundary temperature and employing Laplace transform techniques, the time-dependent temperature is obtained. In a special case, by assuming the material properties to follow a power-law function, the Navier equation is solved for an arbitrary time which led to radial displacement, radial stress, and hoop stress as a function of radial direction.In the numerical results calculated by FEM software ABAQUS is compared to the analytical results. The present results agree well with existing analytical results.
Thick-walled sphere
FGM
FEM
Linearly time-dependent temperature
2015
10
01
1801
1812
http://scientiairanica.sharif.edu/article_3743_12836825da1a57f590c8e93a6301b320.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2015
22
5
A REVIEW ON ELECTRICAL DISCHARGE MACHINING SERVOMECHANISM SYSTEM
Nor Liyana Safura
Hashim
Azli
Yahya
Md. Razak
Daud
Syahrullail
Samion
Ameruddin
Baharom
Nor Hisham
Haji Khamis
Nazriah
Mahmud
Electrical discharge machining is a non-contact process based on thermoelectric energy between the electrode and workpiece. It is an efficient machining process to machine an advanced difficult-to-machine material with high precision, complex shapes and high surface quality. Realizing the advantages and abilities of this machining method, electrical discharge machining research has drawn an interest of many researchers. This paper reviews on the electrical discharge machining process, recent research fields and inventions that have been developed in order to improve workpiece surface quality and integrity, machining time, tool wear and material removal rate. Then, electrical discharge machining apparatus and its servomechanism system including the mechanical structure developments using computer numerical control, lead-screw mechanism, linear motor driven and piezoelectric actuator are reviewed in this paper. Furthermore, control strategies that were applied in electrical discharge machining system including servo-drive control and optimization techniques such as fuzzy, genetic algorithm and artificial neural network are also discussed.
Electrical discharge machining
servomechanism
precise positioning system
micro machining
2015
10
01
1813
1832
http://scientiairanica.sharif.edu/article_3744_48ee7b922e2ecf0e56bb094872daf83b.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2015
22
5
A Mass-Spring-Damper Model for Real Time Simulation of the Frictional Grasping Interactions between Surgical Tools and Large Organs
Hossein
Dehghani Ashkezari
Alireza
Mirbagheri
Saeed
Behzadipour
Farzam
Farahmand
Considering the loss of direct visual and tactile information, surgeons require special training programs to obtain sufficient proficiency for laparoscopic surgery. Surgical training simulation systems provide an effective alternative to animal models for repetitive training practices. The purpose of this study was to develop a biomechanical model of large soft organs for simulation of the interactions of a surgical grasper and spleen in real-time. The mechanical behavior of the spleen was molded in detail, including its nonlinear hyper viscoelastic properties, using a mass-spring-damper model. A novel collision detection algorithm was used to determine the tool-tissue contact zones. Force-based and geometry-based boundary conditions were imposed at the contact nodes, respectively, to represent slippage-included and slippage-free grasping conditions. The model’s predictions were validated against the experimental results on a synthetic test sample. Results of simulation of interactions between the grasping tool and the spleen organ indicated that the non-linear rate dependent and stress relaxation behaviors of the tissue was well depicted by the model. Also, the model was capable of reflecting the effect of tool-tissue friction coefficient on the slippage-free or slippage-included grasping behaviors.
Surgery Simulation
Virtual Environment
Large Intra-abdominal Organs
large deformation
Mass-Spring-Damper Model
2015
10
01
1833
1841
http://scientiairanica.sharif.edu/article_3745_db62ab03999b97bfb3dc145cc963cf01.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2015
22
5
Optimization of power train and control strategy of hybrid electric vehicles
M.
Delkhosh
M.
Saadat-Foumani
P.
Rostami
This paper aims to optimize the transmission and control strategy of a parallel hybrid electric vehicle in order to minimize Fuel Consumption (FC) and emissions, simultaneously. Vehicle transmission is a Power Split Continuously Variable Transmission (PS-CVT), while the employed Torque Coupler (TC) is a two-speed TC. Using this type of TC increases designer ability to create a more ecient transmission. In this vehicle, the electric assist control strategy is used as the control strategy. In this strategy, the engine operates at optimal operation points, obtained using the Global Criterion method (GC). A multi-objective optimization is implemented using GC to minimize vehicle FC and emissions without sacricing dynamic performance. Finally, results of the conventional method of hybrid vehicle optimization and the results of using the Dynamic Programming method are compared.
Hybrid electric vehicle
fuel consumption
Power split continuously variable transmission
Control strategy
Electric assist control strategy
Optimization
2015
10
01
1842
1854
http://scientiairanica.sharif.edu/article_3746_89a66d216ec3914f529e828aac10e98e.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2015
22
5
Analysis,modeling, manufacturing&control of an elastic actuator for rehabilitation robots
Mohammad D.
Hasankola
Abbas
Ehsaniseresht
Majid
M.Moghaddam
A.
Mirzaei Saba
In this paper, modelling and control of an elastic actuator are investigated. First, the required performance of the actuator is determined and then a model of the actuator is proposed. Further, a control algorithm is presented to meet the required performance specifications. A speed feedback and a PI controller are utilized. Moreover, a PID controller is used to control the actuator output torque. Experimental tests are performed on the actuator to validate the actuator performance. First, an accuracy evaluation test is performed on the actuator to calibrate the torque measured by the spring. The results exhibit the spring’s linear characteristics and the capability of torque measurement. Second, the bandwidth of the actuator is measured through sinusoidal input. The results show that the actuator is capable of delivering the required torque in the frequency range of rehabilitation. Third, an impedance measurement test is performed on the actuator indicating that it is capable of exerting the lowest and or highest resistance on patient movement if required. As a result, it is shown that the proposed actuator can satisfy the whole rehabilitation requirements appropriately.
Elastic actuator
Bandwidth
Rehabilitation
impedance control
2015
10
01
1855
1865
http://scientiairanica.sharif.edu/article_3747_47e262536f2da1f809ec573229555665.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2015
22
5
Viscoelasticity effects on hydrodynamic characteristics of electrokinetically driven flow in rectangular microchannels
M.M.
Heydari
The biomicro fluidic devices utilizing electroosmosis for flow actuation are usually encountered with non-Newtonian behavior of working uids. Hence, studying the flow of non-Newtonian fluids under an electroosmotic body force is of high importance for accurate design and active control of these devices. In this paper, mixed electroosmotically and pressure driven flow of two viscoelastic uids, namely PTT and FENE-P models, through a rectangular microchannel is examined. The governing equations in dimensionless form are numerically solved through a finite dierence procedure for a non-uniform grid. It is observed that although the Debye-Huckel linearization fails to predict the velocity prole for viscoelasticuids, this approximation holds even at high zeta potentials, provided the velocity field is normalized with the mean velocity. It is also revealed that the dependency of the mean velocity on the level of elasticity in the fluid is linear. This functionality results in a Poiseuille number independent of the level of elasticity in the fluid. Moreover, the pressure eects are pronounced for higher values of the channel aspect ratio. In addition, both the mean velocity and the Poiseuille number are increasing functions of the channel aspect ratio.
Electroosmotic flow
Micro fluidics
Numerical Modeling
PTT model
FENE-P model
2015
10
01
1866
1876
http://scientiairanica.sharif.edu/article_3748_e4184412dd73317d5bd85cf8dacd9b24.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2015
22
5
Lattice Boltzmann simulation of three-dimensional capsule deformation in a shear flow with different membrane constitutive laws
Zahra
Hashemi
Mohammad
Rahnama
Saeed
Jafari
In this paper, deformation of an elastic spherical capsule suspended in a shear flow is studied in detail using Lattice Boltzmann method for fluid flow simulation, immersed boundary method for fluid-membrane interaction and finite element method for membrane force analysis. While Lattice Boltzmann method is capable of implementing inertia effects, computations were carried out for small Reynolds number in which inertia effects are negligible. Effect of three membrane constitutive equations on capsule deformation, including Neo-Hookean, zero-thickness shell approximation and Skalak’s law with different area-dilation modulus, are studied in detail. Results presented in the form of Taylor deformation parameter, inclination angle and period of tank-treading motion of capsule, show close agreement between those obtained from Neo-Hookean and zero-thickness shell approximation with previous published ones. Such agreement is partially observed for Skalak’s law implementing different area-dilation modulus. In general, behavior of all three constitutive laws are similar for nondimensional shear rates of less than 0.05 while some differences were observed for its values of 0.1 and 0.2. As an efficient computational framework, it is shown that combined Lattice Boltzmann, Immersed Boundary and Finite element method is a promising method for such flow configuration, implementing different membrane constitutive laws.
Lattice Boltzmann method
Immersed boundary method
Capsule deformation
Shear flow
Finite Element Method
2015
10
01
1877
1890
http://scientiairanica.sharif.edu/article_3749_6f91e23a408f337052fd7c2c288a86de.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2015
22
5
An efficient three-axis numerically controlled rough-cutting machining approach on five-axis machine for an integral centrifugal impeller
Yuan
Chen
Guifu
Mei
Jiabin
Wang
Chunyang
Yao
Jun
Gao
To improve the machining efficiency for the conventional five-axis numerically controlled (NC) machining of a centrifugal impeller, this paper presents an efficient simultaneous three-axis NC machining approach on five-axis machine instead of simultaneous five-axis NC machining technology. On the basis of the characteristic curves of an impeller and its projection graphs, a rough-cut surface of the blades is partitioned into several unit machining regions (UMRs). The rotating and tilting angles of a five-axis machine bed are calculated and fixed in advance to support the simultaneous three-axis NC machining of each UMR. The tool paths with the zigzag shape are generated to avoid interference and collision between the cutter and the impeller blades based on the simultaneous three-axis control approach on five-axis machine bed. A prototype model of an impeller with nine blades is established, and its final tool paths in each UMR are verified by means of a cutting simulation function on Vericut software. Simulation results demonstrate that the simultaneous three-axis machining approach on five-axis machine bed can significantly improve the machining efficiency compared to the conventional five-axis machining technology.
Centrifugal impeller
Unit machining regions (UMRs)
Simultaneous three-axis NC machining
five-axis machining
Cutting simulation on Vericut software
2015
10
01
1891
1898
http://scientiairanica.sharif.edu/article_3750_d2fd5fe4d369e24526082a4a9790399d.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2015
22
5
Fahraeus-Lindqvist effect in an Oldroyd 8-constant fluid
M.
Sajid
N.
Ali
A.M.
Siddiqui
Z.
Abbas
A pressure driven axisymmetric flow in a circular tube, having a non- Newtonian Oldroyd 8-constant fluid in the core, is considered in this paper. The Oldroyd 8-constant fluid is surrounded by a Newtonian fluid in the present study. The exact solution of the governing equation is obtained in the form of an integral which is evaluated using Gaussian quadrature. The expression for the apparent viscosity is obtained. The graphical results are presented for the proles of apparent viscosity for different values of the material parameters plotted against tube radius. It is found that for all the values of the material parameters, the apparent viscosity decreases as the tube radius decreases which is the Fahraeus-Lindqvist effect. The results for the case, when there is no Newtonian fluid present in the periphery, are also deduced.
Fahraeus-Lindqvist effect
Oldroyd 8-constant fluid
axisymmetric flow
exact solution
2015
10
01
1899
1903
http://scientiairanica.sharif.edu/article_3751_8109b82a030f3a506f39c9cf7465d0ed.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2015
22
5
Numerical Analysis of a Non-Contact Surface Adhesion System based on Vortex Cup for Wall Climbing Robots
A.
Fallah
M.
Rezasoltani
A.
Riasi
H.
Moradi
In this work, an adhesion system for wall climbing robots using vortex cup has been designed and numerically simulated. A small scale model of the system has been designed and the flow patterns including pressure and velocity fields are computed using CFD analysis. The results are verified using mesh independency and validated through comparison with the available experimental data and show to have high correlation together. Then a large scale vortex cup based on an actual weight of a wall climbing robot has been designed and simulated. Furthermore, the effects of different parameters such as the number of nozzles, cup height and cup radius on the adhesion force have been studied. Finally, a new cup has been designed base on the optimum data obtained from the numerical results.
Robot
vortex cup
wall climbing
CFD
non-contact adhesion
2015
10
01
1904
1910
http://scientiairanica.sharif.edu/article_3752_01044e0c2a999e554b8b28207a0bbdfc.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2015
22
5
Application of Variational Iteration Method to large vibration analysis of slenderness beams considering mid-plane stretching
M.
Daeichi
M.T.
Ahmadian
In this paper nonlinear vibration of transversely vibrated beam with large slenderness and immovable ends is analyzed using Variational Iteration Method (VIM). The nonlinear partial differential equation of motion is converted to a set of coupled ordinary differential equations using Galerkin technique. Two mode expansion for the system response is considered and second order analytical solution of the equations is obtained using VIM. Two algebraic coupled equations are also developed to find the nonlinear frequencies of the system. Numerical Simulations are performed for various initial conditions. Close agreement between the numerical and analytical results is achieved. Also the frequency analysis is performed for a range of initial amplitudes of vibration.
Large Vibration
Variational Iteration Method
Nonlinear Natural Frequency
Galerkin technique
2015
10
01
1911
1917
http://scientiairanica.sharif.edu/article_3753_6c74571a61a48e0a1ae27790f473cd96.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2015
22
5
Analysis of Hydrodynamics and Noise Prediction of the Marine Propellers under Cavitating and Non-cavitating Conditions
M.R.
Bagheri
M.S.
Seif
H.
Mehdigholi
O.
Yaakob
Marine propeller hydrodynamics and noise study is an important problem in the suitable performance of ships and submarines. In the first step of this paper, the hydrodynamics of two propellers was studied under different operating conditions.Thensheet cavitation inception and development conditions were obtained in order to understand the impact of varying rotational speed of the propeller and pressure drop on the propeller noise. In the second step overall sound pressure levels (SPLs) under non-cavitating and sheet cavitating conditions were extracted for each of these models. The overall SPLs were calculated from Ffowcs Williams and Hawkings(FW-H) equations and its integral solutions. In this work, the flow field was analysed with the FVM, and then flow data including; pressure fluctuations, sheet cavitation volume and velocity magnitude results of the flow solution were used as the input for the FW-H formulation to predict the overall SPLs. The results from flow analysis are significant since they are used as noise sources in the FW-H equations to obtainthe overall SPLs. Therefore, these results must be thoroughly analysed. The numerical hydrodynamics results were compared with experiment results for the two propellers and a good agreement was found.
FVM
FW-H
Cavitation
propeller hydrodynamics
propeller noise
2015
10
01
1918
1930
http://scientiairanica.sharif.edu/article_3754_c77aa56a6301e806ab4d058ca8b970e2.pdf