Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
16
2
2009
04
01
Design of a Mathematical Model to Minimize Air Pollution Caused by Job Trips in Mega Cities
EN
M.
Shafiepour
Faculty of Engineering,University of Tehran
wvcagnmo@scientiaunknown.non
M.
Mahmoudi
Department of Science,University of Tehran
okvxsacr@scientiaunknown.non
M.
Abbaspour
Department of Mechanical Engineering,Sharif University of Technology
m-abbaspour@jamejam.net
T.
Dana
School of Energy Engineering,Azad University
khzmxrhs@scientiaunknown.non
Abstract. Urban transportation is one of the main sources of air pollution in mega cities, and urban
job related trips can eectively in
uence the state of air quality. Tehran, the capital of Iran, with a
population of 7.3 million, was selected for this study. The present model is designed to investigate the
eect on trac of the business working hours of dierent occupations and, as a result, on the status of
air pollution. Daily job, non-job and recreational trips using the present vehicle
eet is a major factor
aecting air pollution in Tehran. In the context of the present study, the necessary information was
utilized to dene some relations between job trips and pollutant emissions. The result showed that a
proper adjustment of opening hours for dierent jobs can result in a reduction of pollutant emissions by
as much as 20% during daily trac peak hours.
mathematical model,air pollution,Job trips,Trac control measures
http://scientiairanica.sharif.edu/article_3000.html
http://scientiairanica.sharif.edu/article_3000_25de5e943cd52701d07453d8898b5f02.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
16
2
2009
04
01
Free Vibration Analysis of Rotating Laminated Cylindrical Shells Under Dierent Boundary Conditions Using a Combination of the Layerwise Theory and Wave Propagation Approach
EN
M.T.
Ahmadian
Department of Mechanical Engineering,Sharif University of Technology
email@email.com
Abstract. In this paper, vibration analysis of rotating laminated composite cylindrical shells using
a combination of the layerwise theory and wave propagation approach is investigated. This combination
enables us to study all the conventional boundary conditions in our analysis. Results obtained have been
compared with those available in the literature and a good agreement has been observed. In contrast
to the Equivalent Single Layer theories (ESL), the layerwise theory is constructed on the basis of C0-
continuity through the laminate thickness. For the surface of the shell, a displacement eld based on
the wave propagation approach is proposed. The eect of Coriolis and centrifugal accelerations on the
circumferential and longitudinal modes is investigated. At high rotational speeds, the stationary frequency
is smaller than both the forward and backward frequencies and this dierence increases with the increase
of rotational speed. The in
uence of boundary conditions on the frequencies is more signicant at lower
circumferential modes but at higher modes the eect of the boundary condition is innitesimal.
Rotating laminated cylindrical shells,Layerwise theory,wave propagation
http://scientiairanica.sharif.edu/article_3001.html
http://scientiairanica.sharif.edu/article_3001_6b17509cc342296326b51e9db030b7c1.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
16
2
2009
04
01
Traveling Wave Solutions of the Sine-Gordon and the Coupled Sine-Gordon Equations Using the Homotopy-Perturbation Method
EN
D.D.
Ganji
Department of Mechanical Engineering,Abhar Islamic Azad University
ddg_davood@yahoo.com
A.
Sadighi
Department of Mechanical Engineering,University of Alberta
B.
Ganjavi
Department of Civil Engineering,University of Alberta
zwtvguxl@scientiaunknown.non
Abstract. In this research, the Homotopy-Perturbation Method (HPM) has been used for solving sine-
Gordon and coupled sine-Gordon equations, which have a wide range of applications in physics. HPM
deforms a dicult problem into a simple one which can be easily solved. The results obtained by HPM are
then compared with those of the Adomian Decomposition Method (ADM). The method has been shown to
eectively, easily and accurately solve a large class of nonlinear problems with approximations converging
rapidly to accurate solutions.
Sine-Gordon equation,Coupled sine-Gordon equation,Homotopy-perturbation method,Traveling wave solution
http://scientiairanica.sharif.edu/article_3002.html
http://scientiairanica.sharif.edu/article_3002_febfe68a65cc38d579da78f1d44623d4.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
16
2
2009
04
01
The Eect of Wake Flow and Skew Angle on the Ship Propeller Performance
EN
H.
Ghassemi
Department of Marine Technology,Amirkabir University of Technology
email@email.com
Abstract. This paper provides an investigation into the in
uence of wake and skew on a ship propeller
performance, based on the potential Boundary Element Method (BEM). Two types of in
ow wake from a
ship (i.e. Seiun-Maru and MS689) have been investigated for two propeller types; a Conventional Propeller
(CP) and a Highly Skewed Propeller (HSP). The computed results include pressure distribution, open
water characteristics and thrust
uctuation for one blade and for all blades of the propeller. Calculations
of the unsteady pressure distributions, thrust and torque are in good agreement with experimental data.
In addition, the eect of propeller skew angle on the performance of thrust and torque, is investigated.
Skewed propeller,In ow wake,Hydrodynamic performance
http://scientiairanica.sharif.edu/article_3003.html
http://scientiairanica.sharif.edu/article_3003_8fe0197aa7f5dedeb795fd7722315588.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
16
2
2009
04
01
Simulation of Turbulent Flow Through Porous Media Employing a v2f Model
EN
S.
Kazemzadeh Hannani
Department of Mechanical Engineering,Sharif University of Technology
email@email.com
R.
Bahoosh Kazerooni
Department of Mechanical Engineering,Sharif University of Technology
sfyiswmz@scientiaunknown.non
Abstract. In this article, a v2f model is employed to conduct a series of computations of incompressible
ow in a periodic array of square cylinders simulating a porous media. A Galerkin/least-squares nite
element formulation employing equal order velocity-pressure elements is used to discretize the governing
equations. The Reynolds number is varied from 1000 to 84,000 and dierent values of porosities are
considered in the calculations. Results are compared to the available data in the literature. The v2f model
exhibits superior accuracy with respect to k????" results and is closer to LES calculations. The macroscopic
pressure gradients for all porosities studied showed a good agreement with Forchheimer-extended Darcy's
law in the range of large Reynolds numbers.
porous media,Turbulent ow,Volume averaging,v2f model
http://scientiairanica.sharif.edu/article_3004.html
http://scientiairanica.sharif.edu/article_3004_d262d099b668f8d9d980fcf69f2ffd37.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
16
2
2009
04
01
Spectator Model in D Meson Decays
EN
H.
Mehrban
Department of Physics,Semnan University
hmehraban@semnan.ac.ir
Abstract. In this research, the eective Hamiltonian theory is described and applied to the calculation
of current-current (Q1;2) and QCD penguin (Q3; ;6) decay rates. The channels of charm quark decay in
the quark levels are: c ! dud, c ! dus, c ! sud and c ! sus where the channel c ! sud is dominant.
The total decay rates of the hadronic of charm quark in the eective Hamiltonian theory are calculated.
The decay rates of D meson decays according to Spectator Quark Model (SQM) are investigated for the
calculation of D meson decays. It is intended to make the transition from decay rates at the quark level to
D meson decay rates for two body hadronic decays, D ! h1h2. By means of that, the modes of nonleptonic
D ! PV , D ! PP, D ! V V decays where V and P are light vector with JP = 0???? and pseudoscalar
with JP = 1???? mesons are analyzed, respectively. So, the total decay rates of the hadronic of charm quark
in the eective Hamiltonian theory, according to Colour Favoured (C-F) and Colour Suppressed (C-S) are
obtained. Then the amplitude of the Colour Favoured and Colour Suppressed (F-S) processes are added
and their decay rates are obtained. Using the spectator model, the branching ratio of some D meson
decays are derived as well.
Eective Hamilton,c quark,D meson,Spectator model,Hadronic,Colour favoured,Colour suppressed
http://scientiairanica.sharif.edu/article_3005.html
http://scientiairanica.sharif.edu/article_3005_08c853f9ce54fcd4416c2691d3a387be.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
16
2
2009
04
01
Micro Resonator Nonlinear Dynamics Considering Intrinsic Properties
EN
H.
Sayyaadi
Department of Mechanical Engineering,Sharif University of Technology
email@email.com
M.A.
Tadayon
Department of Mechanical Engineering,Sharif University of Technology
imflbbjl@scientiaunknown.non
Abstract. One of the most important phenomena to aect the motion behaviour of Micro Resonators
is their thermal dependency. This has recently received the attention of researchers widely. A thermal
phenomenon has two main eects, the rst is damping, due to internal friction, and the second is
softening, due to Young's modulus-temperature relationship. In this research work, some theoretical and
experimental reported results are used to make a proper model, including thermal phenomena. Two
Lorentzian functions are used to describe the restoring and damping forces caused by thermal phenomena.
In order to emphasize the thermal eects, a nonlinear model of the MEMS, considering capacitor
nonlinearity and mid-plane stretching, has been used. The responses of the system are developed by
employing a multiple time scale perturbation method on a non-dimensionalized form of the equations.
Frequency response, resonance frequency and peak amplitude are examined by varying the dynamic
parameters of the modelled system. Finally, Fuzzy Generalized Cell Mapping (FGCM) is introduced
and applied to the Micro Resonator's dynamical system behaviour. It is then concluded as to how the
model uncertainties and dierent initial conditions can aect the working domain of the system and/or
make it pull in instabilities. At the end, it can be seen that FGCM is a useful method for monitoring the
working regions of Micro Resonators, while varying system parameters.
Micro resonator,Thermal eects,nonlinear dynamics,Fuzzy generalized cell mapping
http://scientiairanica.sharif.edu/article_3006.html
http://scientiairanica.sharif.edu/article_3006_4932296fab63e45befdf4df7d90e3bc4.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
16
2
2009
04
01
Parametric Study of Hot Rolling Process by the Finite Element Method
EN
A.R.
Shahani
Department of Mechanical Engineering,Khajeh Nasire Toosi University of Technology
a.r.shahani@kntu.ac.ir
S. A.
Nodamaie
Department of Mechanical Engineering,Khajeh Nasire Toosi University of Technology
I.
Salehinia
Department of Mechanical Engineering,Khajeh Nasire Toosi University of Technology
htddbjmb@scientiaunknown.non
Abstract. In the present investigation, a hot rolling process of AA5083 aluminum alloy is simulated.
The approach is based on the thermo-mechanical analysis of the problem using the Finite Element Method
(FEM). The temperature distribution in the roll and the slab, the stress, strain and strain rate elds, are
extracted throughout a transient analysis of the process. The main hypotheses adopted in the formulation
are: The thermo-viscoplastic behavior of the material, expressed by the Perzyna constitutive equation and
rolling under plane-deformation conditions. The main variables that characterize the rolling process, such
as the geometry of the slab, load, rolling speed, percentage of thickness reduction, initial thickness of the
slab and friction coecient, have been expressed in a parametric form, giving good
exibility to the model.
The congruence of the results has been evaluated using experimental and theoretical data available in the
literature.
Hot rolling process,Plane strain deformation,Sequential coupling,Contact pressure,Eective stress eld,temperature distribution
http://scientiairanica.sharif.edu/article_3007.html
http://scientiairanica.sharif.edu/article_3007_025c18f907c08b25af1cc556524c79e0.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
16
2
2009
04
01
Direct Design of Branched Ducts
EN
A.
Ashrafizadeh
Department of Mechanical Engineering,Khajeh Nasire Toosi University of Technology
hxastlro@scientiaunknown.non
M.
Taiebi-Rahni
Department of Aerospace Engineering,Sharif University of Technology
taeibi@sharif.edu
F.
Ghadak
Department of Aerospace Engineering,I.P.M.
spnzwpsr@scientiaunknown.non
Abstract. A fully coupled formulation of thermo-
uid shape design problems has recently been
developed in which the unknown nodal coordinates appear explicitly in the formulation of the problem.
This direct design" approach is, in principle, generally applicable and has been successfully applied in the
context of potential and Euler
ow models.This paper focuses on the direct design of ducts using the ideal
ow model and may be considered as an addendum to the paper entitled Direct Design of Ducts" [1].
However, a cell-vertex nite volume method is used and a dierent boundary condition implementation
technique is applied, as compared to the method presented in the previous paper. The other new feature
is that a non-linear algebraic method is used for grid generation. The method is also proved to be capable
of designing complex
ow passages, such as branched ducts.
Fully-coupled inverse method,Direct design,Internal ow,Stagnation point
http://scientiairanica.sharif.edu/article_3008.html
http://scientiairanica.sharif.edu/article_3008_e0e25cdc1622d650fc7150a54b89435e.pdf