eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-04-01
23
2
559
565
10.24200/sci.2016.3843
3843
Fluid–structure interaction analysis of a piezoelectric flexible plate in a cavity filled with a fluid
Y. Amini
aminiyaser@shirazu.ac.ir
1
H. Emdad
hemdad@shirazu.ac.ir
2
M. Farid
farid@shirazu.ac.ir
3
Iran- Shiraz- Shiraz University- school of Mechanical Engineering
Iran- Shiraz- Shiraz University- school of Mechanical Engineering
Iran- Shiraz- Shiraz University- school of Mechanical Engineering
This study presents a numerical analysis of fluid- structure interaction whose structure is a flexible piezoelectric material. Piezoelectric materials are widely used in aeroelasticity and turbomachinery fields for vibrational, flutter and noise control. In this work a FSI benchmark is revised to contain the piezoelectric materials. The influence of piezoelectricity on the oscillation of the structure and fluid flow is considered. For validation, two benchmark problems are solved and results of the present code are compared with those of the previous works. Current results show that the piezoelectric behavior of a plate significantly influences the oscillation of the plate and the fluid flow properties.
http://scientiairanica.sharif.edu/article_3843_2983ce88a3477b9c43a41300116cead0.pdf
Fluid–structure interaction
piezoelectric actuators
Smart materials
large structural deformations
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-04-01
23
2
566
574
10.24200/sci.2016.3844
3844
Improvement of TFT-LCD's polarizer plate bubble problem using a preheating-process
Chern-Sheng Lin
lincs@fcu.edu.tw
1
Jung-Ti Huang
2
Pin Yi Wu
3
Yun-Long Lay
4
Hung-Jung Shei
5
Department of Automatic Control Engineering, Feng Chia University. Taichung, Taiwan
Department of Automatic Control Engineering, Feng Chia University. Taichung, Taiwan
Department of Automatic Control Engineering, Feng Chia University. Taichung, Taiwan
Dept. of Electronic Engineering, National Chin-Yi University of Technology, Taichung, Taiwan
Department of Mechanical Engineering, China Institute of Technology, Taipei, Taiwan
In this study, improvement of the polarizer plate bubble in the thin film transistor liquid crystal display process, especially where the polarizer plate is attached to the black matrix area at the end of the glass substrate, is presented. This study proposed temperature control functions during the attaching process using the preheating operations of pressure sensitive adhesives and a pre-existing warp polarizer plate. The polarizer plate is softened evenly, and, then, the bubbles can be discharged smoothly in the attaching process. Three main control factors are used in the polarizer plate attachment process, using an experimental design method, to determine the best combination of parameters. By applying optimal parameters in the experiments, bubble width can be decreased by 60.49%, compared with that of the previous process.
http://scientiairanica.sharif.edu/article_3844_e317ea2ce0b76dec943e37c02c5058b4.pdf
Preheating-process
Black matrix area
Polarizer plate
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-04-01
23
2
575
587
10.24200/sci.2016.3845
3845
Investigating the Effects of Ionic Polymer Metal Composite Patches on Aeroelastic Characteristics of a Cantilever Wing in Supersonic Flow
Shahab Jamshidi
1
Morteza Dardel
dardel@nit.ac.ir
2
Mohammad Hadi Pashaei
mpashaei@nit.ac.it
3
Department of mechanical engineering, Babol Noshirvani University of Technology, 47148-71167, Babol, Iran
Department of mechanical engineering, Babol Noshirvani University of Technology, 47148-71167, Babol, Iran
Department of mechanical engineering, Babol Noshirvani University of Technology, 47148-71167, Babol, Iran
This work presents energy harvesting from limit cycle oscillation of low aspect ratio rectangular cantilever wings in supersonic flow. The wing is modeled in according to classical plate theory with Von-Karman strain-displacement relations for modeling large deflections due to mid plane stretching. The aerodynamic pressure is evaluated based on the quasi-steady first-order piston theory. Linear and nonlinear aeroelastic characteristics of the considered model are accurately examined and the effects of ionic polymer metal composite (IPMC) energy harvesting on flutter margin and limit cycle oscillation amplitudes are investigated. It is shown that position of IPMC on the wing has a great effect on the amount of harvested power. Since IPMC induces a high level of strain, it produces static deflection of wing. This static deflection produces stiffness hardening of the entire system, and accordingly can greatly reduce the amplitude of limit cycle oscillation. Obtained results show that IPMC actuator has more influence on limit cycle oscillation of wing, while its effect on flutter instability is negligible.
http://scientiairanica.sharif.edu/article_3845_7ec25aebfd3f18eef679db5063716e2f.pdf
energy harvesting
IPMC
flutter
limit cycle
supersonic flow
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-04-01
23
2
588
599
10.24200/sci.2016.3846
3846
First-Order Optimal Line-of-Sight Guidance for Stationary Targets
S. H. Jalali-Naini
shjalalinaini@modares.ac.ir
1
S. H. Sajjadi
h.sajjadi@modares.ac.ir
2
Faculty of Mechanical Engineering, Tarbiat Modares University, P.O. Box: 14115-111, Tehran, Iran
Faculty of Mechanical Engineering, Tarbiat Modares University, P.O. Box: 14115-111, Tehran, Iran
In this paper, a closed-loop optimal line-of-sight guidance law for first-order control systems is derived for stationary targets. The problem is solved for the one-dimensional case using normalized equations to obtain normalized guidance gains and performance curves. Three sets of normalized equations are introduced and discussed using different normalizing factors. The performance of the guidance laws are compared in normalized forms with zero-lag optimal guidance and first-order optimal scheme with steady-state gains using a second-order control system. Normalized miss distance analysis shows that the miss distance of the first-order guidance law is smaller than the two mentioned schemes for small total flight times.
http://scientiairanica.sharif.edu/article_3846_e753b5fd15fb0cf1b25f083d830a9180.pdf
Line-of-Sight Guidance
Optimal Guidance
Normalized Miss Distance Analysis
First Order Control System
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-04-01
23
2
600
608
10.24200/sci.2016.3847
3847
An Alternative Mechanism for the formation of High Density Lipoprotein in Peripheral Tissues
B. Damirchi
1
M. S. Saidi
mssaidi@sharif.edu
2
M. Rismanian
3
M. Amininasab
4
Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
Department of Cell and Molecular Biology, Faculty of Science, University of Tehran, Tehran, Iran
High Density Lipoprotein (HDL) is a lipid-protein complex which is responsible to transport cholesterol and triglyceride molecules due to the inability of these compounds to dissolve in aqueous environment such as bloodstream. Among renowned probable structures, belt like structure is the most common shape which is proposed to this vital bimolecular complex. In this structure, the protein scaffold encompasses the lipid bilayer and a planar circular structure is formed. Several HDL simulations with embedded components in lipid section were performed. Here we applied a series of molecular dynamics simulations using MARTINI coarse grain force field to investigate an HDL model with pore of different radiuses in bilayer section instead of embedding components. The results of such studies revealed the probable structural modes in HDL configurations. In addition, totally 2.5 µs simulations lead to study the ratio of lipids to protein in HDL conformation and determine the structural shape of HDL and stability of each model due to atomic interactions. Furthermore, we proposed new conformation for HDL in its initial steps of constructing outside of cells and in peripheral tissues.
http://scientiairanica.sharif.edu/article_3847_e5d00752d31916b9b5ff2a9219e7ceae.pdf
High Density Lipoprotein
Structural modes
Lipid protein complex
assembly
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-04-01
23
2
609
617
10.24200/sci.2016.3848
3848
ESTIMATION OF MECHANICAL PROPERTIES OF WELDED S355J2+N STEEL VIA THE ARTIFICIAL NEURAL NETWORK
Hakan ATES
hates@gazi.edu.tr
1
Bekir DURSUN
bekirdursun_@hotmail.com
2
Erol KURT
ekurt@gazi.edu.tr
3
Gazi University, Technology Faculty, Department of Metallurgical and Material Engineering, Teknikokullar 06500 Ankara, Turkey
Gazi University, Institute of Sciences and Technology, Department of Electrical Education, Teknikokullar 06500 Ankara, Turkey
Gazi University, Technology Faculty, Department of Electrical and Electronics Engineering, Teknikokullar 06500 Ankara, Turkey
A new estimation study on the material features for the welding processes is reported. The method bases on the artificial neural network (ANN) for the estimation of material features after in the gas-metal arc welding process. Since the welding is a very common process in many engineering areas, this method would certainly assist the technicians and engineers to estimate the material features related to the welding parameters before any welding operation. In the proposed method, the input parameters of welding are defined as various shielding gas mixtures of Ar, O2 and CO2. As the resulting feature, the estimation is made on the mechanical properties such as tensile strength, impact test, elongation and weld metal hardness following ANN. The controller is trained with the scaled conjugate gradient method. It is proven that some estimated values are consistent with the experimental data, whereas some others have relatively higher errors. Thus, this method can be used to estimate especially the yield strength and elongation values, when the shielding gas proportions are ascertained before the welding, thereby the method helps to ascertain the welding gas selection in a very short time for engineers and assists to decrease the welding costs.
http://scientiairanica.sharif.edu/article_3848_d0d0c1a9f002fb6f3e22f766be77279a.pdf
Welding
yield strength
impact test
Hardness
elongation
ANN
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-04-01
23
2
618
632
10.24200/sci.2016.3849
3849
Numerical prediction of thermo-aeraulic behavior for a cavity with internal linear heat source
C. Teodosiu
1
D. David
2
R. Teodosiu
3
Faculty of Building Services and Equipment, Technical University of Civil Engineering, Bucharest 020396, Romania
Universite de Lyon, 69361 Lyon Cedex 07, France
Faculty of Building Services and Equipment, Technical University of Civil Engineering, Bucharest 020396, Romania
Computational Fluid Dynamics (CFD) is a promising way, nowadays, to predict the air Flow in enclosures. As a result, the objective of this study is to assess the potential of CFD technique to predict the air Flows driven by buoyancy in heated real-scale rooms. The numerical model is validated using experimental data for fullscale test rooms; therefore, the experimental set-up is rst presented. This is followed by the numerical model description, focusing on its principal elements: computational domain geometry, discretization, turbulence model, radiation model, and thermal boundary conditions. In addition, a simplied approach is proposed to integrate a heat source in CFD models: Term source homogeneously spread all over the volume of the heat source. Comprehensive experimental-numerical comparisons are presented in terms of heat transfer to the walls of the test room, heat source behavior, and plume development. The results show that the model developed in this study leads to realistic predictions. Finally, the simplied CFD description of heat sources developed here can be extrapolated for other congurations - dierent power, heat emission (convection/radiation), dimensions, and shape. Consequently, this method can be applied in detailed studies dealing with thermal comfort, indoor air quality, and energy consumption for heated rooms.
http://scientiairanica.sharif.edu/article_3849_d41d8cd98f00b204e9800998ecf8427e.pdf
Computational Fluid Dynamics modeling (CFD)
Transition SST k-w turbulence model
DO radiation model
Experimental full-scale room
Buoyancy-driven cavity
Linear heat source
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-04-01
23
2
633
647
10.24200/sci.2016.3850
3850
Forced vibration analysis of a system equipped with the nonlinear displacement-dependent (NDD) damper
Javad Jahanpour
jahanpourfr@mshdiau.ac.ir
1
Mojtaba Porghoveh
mdj.prg@hotmail.com
2
Shahab Ilbeigi
ilbeigi@my.uri.edu
3
Islamic Mashhad Branch, Azad University of Mashhad
In this paper, forced vibration analysis of a mass-spring system equipped with a nonlinear displacement-dependent (NDD) damper is elaborated. To this end, the nonlinear governing differential equation of the system is derived for two types of soft- and hard- periodic excitations. In order to obtain the displacement of the excited system, the approximate analytical solution of the governing equation is developed using the multiple scales method (MSM). The proposed analytical formulations are performed for several cases of hard- and soft-excitation and are also verified by the numerical fourth-order Runge-Kutta method. Moreover, the performance of the NDD damper is analyzed and compared with the traditional linear damper used in the both hard- and soft-excited vibration analyses. For a same external periodic force, a comparison has also been carried out between the responses of the hard- and soft-excitations. It is found that the organizing the external force based on its amplitude into two types as soft- and hard- excitation, leads to a better estimated response in the forced vibration analysis. Moreover, the NDD damper has a superior performance in reducing the vibration amplitude thorough tending to the steady-state solution compared to the traditional linear damper.
http://scientiairanica.sharif.edu/article_3850_d8ce54b4bf29264e57c9907a7145451e.pdf
Nonlinear displacement-dependent (NDD) damper
Forced vibration analysis
Hard- and Soft- excitation
Multiple scales method
Vibration reduction
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-04-01
23
2
648
657
10.24200/sci.2016.3851
3851
A novel computational framework to approximate analytical solution of nonlinear fractional elastic beam equation
K. Sayevand
ksayehvand@malayeru.ac.ir
1
K. Pichaghchi
2
Faculty of of Mathematical Sciences, University of Malayer, P. O. Box 16846-13114, Malayer, Iran
Faculty of of Mathematical Sciences, University of Malayer, P. O. Box 16846-13114, Malayer, Iran
In this paper, the generalized travelling solutions of the nonlinear fractional beam equation is investigated by means of homotopy perturbation method. The fractional derivative is described in the Caputo sense. The reliability and potentiality of the proposed approach which is based on joint Fourier-Laplace transforms and homotopy perturbation method will be discussed. The solutions can be approximated via an analytical series solution. Moreover, convergence and stability of the proposed approach for this equation is investigated. The results reveal that the proposed scheme is very effective and promising.
http://scientiairanica.sharif.edu/article_3851_bb4b91c36f7002a710640f39c573fe57.pdf
Caputo fractional derivative
Nonlinear elastic beam equation
Fourier transform
Laplace trans- form
Homotopy perturbation method
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-04-01
23
2
658
667
10.24200/sci.2016.3852
3852
Modeling Paramecium swimming in a capillary tube
Ali N. Sarvestani
1
Amir Shamloo
shamloo@sharif.edu
2
Mohammad Taghi Ahmadian
ahmadian@sharif.edu
3
Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
In certain types of biomimetic surgery systems, micro robots inspired by Paramecium are designed to swim in a capillary tube for gaining access to internal organs with minimal invasion. Gaining insights into the mechanics of Paramecium swimming in a capillary tube is vital for optimizing the design of such systems. There are two approaches to modeling the physics of micro swimming. In the envelope approach which is widely accepted by researchers, Paramecium is approximated as a sphere self-propelled by tangential and normal surface distortions. Not only this approach is incapable of considering the specific geometry of Paramecium, but also it neglects short range hydrodynamic interactions due to beating cilia. Thus it leads to dissimilarity between experimental data and simulation results. In this study, it is aimed to present a sub layer approach to modeling Paramecium locomotion which is capable of directly applying the hydrodynamic interactions due to beating cilia on Paramecium boundary. In this approach, Paramecium’s boundary is discretized to hydrodynamically independent elements; in each time step of swimming, a specific function is fit to Paramecium boundary. Then, element coordinates are extracted and fluid dynamic equations are solved to model the physics of micro swimming.
http://scientiairanica.sharif.edu/article_3852_5bbb7366ba638226b3c3f918346fdae8.pdf
Paramecium
swimming
modeling
modified boundary element
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-04-01
23
2
668
677
10.24200/sci.2016.3853
3853
A Novel Method for Maximum Lift Prediction in High-Lift Configurations
Mahmoud Pasandideh Fard
1
Seyyed Ali Sahaf
2
Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
Many decisions in the preliminary design steps of an aircraft are very hard to take, due to a lot of unknown variables at this stage. These early decisions can be made more reliable by testing different configurations by numerical methods repetitively. Therefore it is very important to have a rapid, reliable and particularly easy to implement numerical tool. One of the most important steps in aerodynamic configuration development is design and sizing of the high lift devices. The main criterion for this design is lift increment that a particular configuration can produce. Therefore, it is very important to adequately estimate the maximum lift coefficient for a flapped wing at highly deflected flap configurations.This paper tries to introduce a novel numerical-empirical method for estimation of lift generation capability of a specific high lift device configuration. However, drag production estimation is not in the scope of this paper. In this method the linear portion of the lift curve is derived numerically, while the curved near stall region is estimated through empirical methods. The results are compared with some experimental data to show the method validity.
http://scientiairanica.sharif.edu/article_3853_a9696c53cb227aa111f93a4cb6540b73.pdf
High Lift Device
Aircraft Design
Maximum Lift
Reynolds Average Navier Stokes
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-04-01
23
2
678
684
10.24200/sci.2016.3854
3854
Investigation of the Effect of Walkway Orientation on Natural Ventilation
M. Rismanian
1
A. F Forughi
2
F. Vesali
3
M. S. Mahmoodabadi
4
Faculty of Architecture, Malayer University, Malayer, Hamedan, Iran
Faculty of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
Faculty of Railway Eng., University of Science and Technology, Tehran, Iran
Faculty of Architecture, Tehran University, Tehran, Iran
Proper orientation of walkways based on regional winds and local shades provides a good control over walkways ventilation. Architectures of the old town of Sirjan had experimentally orientated the city’s walkways in a manner that shadows in walkways produced the maximum possible natural ventilation in this hot and dry town. This study has focused on this optimum design of Sirjan city considering natural ventilation mechanism. At first, a typical walkway with certain geometric parameters is considered. Then, considering the symmetry of the shadows cast in walkways, the natural ventilation rate is investigated at 7 different angles with 15° intervals. The problem is modeled using finite volume method numerically with Sirjan climate conditions. Results show that the present orientation of walkways in this city creates the maximum possible rate of natural ventilation and thermal comfort in a walkway.
http://scientiairanica.sharif.edu/article_3854_ceadda300d3bbdcdad42e3e02b5f55f7.pdf
Natural Ventilation
Walkway orientation
free convection
Sirjan
Finite volume