eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2009-06-01
16
3
3211
Three-Dimensional Elasticity Solution for Laminated Cross-Ply Panels Under Localized Dynamic Moment
M. Shakeri
shakeri@cic.aut.ac.ir
1
A. Alibeiglou
a_beigloo@yahoo.com
2
Department of Mechanical Engineering,Amirkabir University of Technology
Department of Mechanical Engineering,Berakly
Abstract. Three-dimensional elasticity solutions have been presented for a thick laminated cross-ply
circular cylindrical panel. The cylindrical panel is under a dynamic localized patch moment, is simplysupported
at all edges and has nite length. Ordinary dierential equations with variable coecients are
formulated using an expansion of Fourier series applied to the displacement eld in circumferential and
axial direction. The resulting ordinary dierential equations are solved by the Galerkin nite element
method. Numerical results are presented for [0/90/0], [90/0/90], [0/90/0/90/0], [0/90/0/90/0/90/0]
and [0/90/0/90/0/90/0/90/0] stacking sequences.
https://scientiairanica.sharif.edu/article_3211_b52c094fe694cf2beed5e6b1893bd574.pdf
dynamic
Patch moment
elasticity
Panel
Multi-layered
Cross-ply
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2009-06-01
16
3
3212
A Numerical Study of Flow and Heat Transfer Between Two Concentric Rotating Spheres with Time-Dependent Angular Velocities
A. Baradaran Rahimi
rahimiab@yahoo.com
1
A. Jabbari Moghadam
oamzflnr@scientiaunknown.non
2
Faculty of Engineering,Ferdowsi University of Mashhad
Faculty of Engineering,Ferdowsi University of Mashhad
Abstract. The transient motion and heat transfer of a viscous incompressible
uid contained between
two concentric spheres, maintained at dierent temperatures and rotating about a common axis with
dierent angular velocities, is considered numerically, when the angular velocities are arbitrary functions
of time. The resulting
ow pattern, temperature distribution and heat transfer characteristics are presented
for the various cases, including exponential and sinusoidal angular velocities. An interesting eect, of
long delays in the heat transfer of a large portion of the
uid in the annulus, is observed, because of the
angular velocities of the corresponding spheres.
https://scientiairanica.sharif.edu/article_3212_3335957cb802f7e579e6d37fd2d847ca.pdf
Flow and heat transfer
Concentric rotating spheres
Time-dependent angular velocities
numerical solution
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2009-06-01
16
3
3213
Radiative Transfer in the Fine Structures of Quiescent Prominences
A. Ajabshirizadeh
vkjderie@scientiaunknown.non
1
A. G. Nikoghossian
vuoggkzr@scientiaunknown.non
2
H. Ebadi
cabrfnww@scientiaunknown.non
3
Department of Physics,Tabriz University
Department of Physics,Tokai University
Department of Physics,Tokai University
Abstract. In this paper, elaborating the statistical approach recently proposed by one of the present
authors (A.G.N) has been elaborated for interpretation of the spatial brightness variations of solar
quiescent prominences. The mean statistical characteristics of the LTE line radiation such as the mean
intensity and its Relative Mean Square Deviation (RelMSD) emerging from a multi-component atmosphere
with randomly varying properties are derived as the functions of the frequency within a line. The results
previously obtained are extended to encompass more realistic models when
uctuations of the observed
line intensities represent a combined eect of variation of dierent physical and geometrical parameters
of the medium (internal energy sources, optical thickness, velocity eld, the number of structural elements
along the line of sight etc.). It is shown that the center-to-wings evolution of the RelMSD essentially
depends on the mentioned features of the atmosphere, which are responsible for the spatial variations we
observe. The obtained results are applied to the EUV-lines through SUMER spectrometer in frameworks
of the SOHO space mission. As a rule, the observed values of RelMSD in the central frequencies of the
observed lines are less than those in the wings. This points out that the observed
uctuations are mainly
due to the changes in energy sources in the prominence. It is shown that the central dispersion of the
RelMSD correlates with the characteristic temperature of a given line formation.
https://scientiairanica.sharif.edu/article_3213_b9b31faac86f39dc3bba9baeac760bd4.pdf
Sun
Radiative transfer
Quiescent prominence
Fine structure
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2009-06-01
16
3
3214
Alumina-Copper Eutectic Bond Strength: Contribution of Preoxidation, Cuprous Oxides Particles and Pores
M.A. Faghihi-Sani
email@email.com
1
H. Ghasemi
hadighasemi@alum.sharif
2
A.H. Kokabi
oagatwpt@scientiaunknown.non
3
Z. Riazi
ejxhbndh@scientiaunknown.non
4
Department of Materials and Engineering,Sharif University of Technology
Department of Materials Science and Engineering,Sharif University of Technology
Department of Materials Science and Engineering,Shiraz University
Research Center,Davis
Abstract. The in
uences of cupric oxide layer thickness, cuprous oxide particles and pores on the
mechanical properties and microstructure of an alumina-copper eutectic bond have been investigated. The
furnace atmosphere in the rst stage was argon gas with 2 10????6 atm oxygen partial pressure. In the
second stage, the furnace atmosphere was the same as the rst stage except that the cooling interval was
between 900-1000C and the hydrogen gas was injected into the furnace atmosphere. Finally, in the last
stage, a vacuum furnace with 5 10????8 atm pressure was chosen for the bonding procedure. The peel
strength of rst stage specimens shows that a cupric oxide layer with 320 25 nm thickness generates
maximum peel strength (13:1 0:3 kg/cm) in the joint interface. In the second stage, by using hydrogen
gas, a joint interface free from any cuprous oxide particles was formed. In this case, the joint strength
has increased to 17:1 0:2 kg/cm. Finally, the bonding process in the vacuum furnace indicates that
the furnace gas does not have a considerable eect on joint interface pores. Furthermore, the bonding
process in the vacuum furnace reduces the peel strength of the joint due to the formation of more pores.
A thorough study of pore formation is presented.
https://scientiairanica.sharif.edu/article_3214_df1a1acd840faf9d366459f656363cb2.pdf
Alumina-copper
Bonding
Peel strength
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2009-06-01
16
3
3215
Investigation of Valve-Closing Law on the Maximum Head Rise of a Hydropower Plant
A. Vakil
email@email.com
1
Department of Mechanical Engineering,Sharif University of Technology
Abstract. Piping systems commonly experience the transient-state situation as the result of changes
to
ow conditions during pump failures, valve closures or turbine load rejection. This paper addresses
transients as a consequence of the load rejection of a Francis hydropower plant (Karun 4, Ahwaz, Iran).
To control the turbine system and related equipment during load rejection, the valve closing law of wicket
gates is of paramount importance. The pressure rise at the end of the pressure shaft, the pressure drop in
the draft tube and the speed rise while the electromagnetic braking torque disappears are solely dependent
on the closing curve. Thus, an optimum closing law can eliminate the probable risk of damage to the
units. This paper develops a computational model to calculate water-hammer system components, such
as pressure rise, speed rise, discharge variations and pressure
uctuations. Results obtained from the
present model are compared and validated with those obtained by a consultant at the Karun project. The
eects of dierent valve-closing laws on the maximum head rise at the end of the pressure shaft and other
components are also investigated.
https://scientiairanica.sharif.edu/article_3215_b03c5281197e80cd21c24ce084881216.pdf
Method of Characteristics
Hydropower plant
Transient ow
Valve-closing law
Karun 4 hydropower plant
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2009-06-01
16
3
3216
Simulation of Random Irregular Sea Waves for Numerical and Physical Models Using Digital Filters
A. Ranginkaman
sansrteg@scientiaunknown.non
1
M.J. Ketabdari
izjgktvt@scientiaunknown.non
2
Faculty of Marine Technology,Amirkabir University of Technology
Faculty of Marine Technology,Amirkabir University of Technology
Abstract. Wind waves, which are one of the most important phenomena in the marine environment,
are generally progressive in nature and can move far distances out of their area of formation. Thus,
an understanding of wave hydrodynamics and their eects is important for engineers in the design and
construction of marine structures and coastal management. Signicant insights may be gained from
numerical and laboratory studies. Often the waves simulated in numerical and physical models do not
have the full characteristics of real sea waves. It is then necessary to present a reliable method of wave
simulation for numerical and laboratory wave
umes. In this paper, the results of numerically simulated
water waves, using digital lters, are presented. A model has been developed to simulate a water wave
prole from dierent target spectra using WNDF methods. The results showed that the WNDF method
involves good stochastic wave characteristics if a suitable spectrum is used as target. The results have
implications for the numerical or laboratory estimation of wave forces on model oshore or coastal
structures.
https://scientiairanica.sharif.edu/article_3216_8321a8f884c237e1fc54caf96452dc0b.pdf
Wave spectrum
Digital lter
White noise
Random irregular waves
WNDF method
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2009-06-01
16
3
3217
A Simulation on the Propagation of Supernova Cosmic Particles in a Fractal Medium
N. Ketabi
niloo_ketabi@yahoo.com
1
J. Fatemi
obkjymsd@scientiaunknown.non
2
Department of Physics,Shahid Bahonar University of Kerman
Department of Physics,Shahid Bahonar University of Kerman
Abstract. In this paper, we present a Mont Carlo simulation by using the inhomogeneous diusion
equation suggested by Lagutin et al. in a fractal interstellar medium for a supernova, as being the main
source of Galactic cosmic rays in an energy range up to 1016ev. When the numerical results of this
simulation are compared with the predicted energy density of cosmic rays from the supernova model of
Erlikyn and Wolfendale (EW), they show a strong consistency with the observed experimental parameters
of cosmic rays, i.e. Galactic radial gradient, percentage of total supernova energy transfer to cosmic
particles etc., which is also conrmation of a supernova being of cosmic ray origin.
https://scientiairanica.sharif.edu/article_3217_77fb5282c4670f4be58124939e35b382.pdf
Cosmic rays
Supernova
Particle propagation
Fractal medium
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2009-06-01
16
3
3218
Reduction of Thermodynamic Losses in a Supersonic Nucleating Steam Nozzle by Spraying Water Droplets
M.R. Mahpeykar
mahpeymr@um.ac.ir
1
E. Lakzian
sfazwndu@scientiaunknown.non
2
E. Amirirad
htmfxrps@scientiaunknown.non
3
Department of Mechanical Engineering,Ferdowsi University of Mashhad
Department of Mechanical Engineering,Ferdowsi University of Mashhad
Department of Mechanical Engineering,Ferdowsi University of Mashhad
Abstract. During the course of expansion of steam in turbines, the vapour rst supercools and then
nucleates to become a two-phase mixture. Formation of the liquid phase causes thermodynamic and
aerodynamic losses in steam turbines. In this study, the treatment is a one-dimensional, non-equilibrium
ow in a steady Laval nozzle. In this paper, the changes in the rate of nucleation, entropy, pressure and
other parameters of the two-phase
ow, subjected to spraying the liquid droplets close to the nozzle's throat,
are investigated. By injecting the water droplets into a supersonic condensing
ow, the thermodynamic
loss is considerably decreased.
https://scientiairanica.sharif.edu/article_3218_6e9e4cb1976d25c7b944d4a3ce9c35ab.pdf
Two-phase ow
Convergent-divergent nozzle
nucleation
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2009-06-01
16
3
3219
Dynamic Green Function Solution of Beams Under a Moving Load with Dierent Boundary Conditions
A. Davar
gnrxrmjk@scientiaunknown.non
1
O. Rahmani
istmcjlu@scientiaunknown.non
2
B. Mehri
3
Department of Mechanical Engineering,Khajeh Nasire Toosi University of Technology
Department of Mechanical Engineering,Khajeh Nasire Toosi University of Technology
Department of Mathematics,Sharif University of Technology
Abstract. This paper presents the linear dynamic response of uniform beams with dierent boundary
conditions excited by a moving load, based on the Euler-Bernouli beam theory. Using a dynamic green
function, eects of dierent boundary conditions, velocity of load and other parameters are assessed and
some of the numerical results are compared with those given in the references.
https://scientiairanica.sharif.edu/article_3219_d007fa9472a219ed083d40c9004456ae.pdf
Beams
Green function
Euler-Bernoulli
Buckling problem
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2009-06-01
16
3
3220
Characterization of Sputtered NiTi Shape Memory Alloy Thin Films
S.K. Sadrnezhaad
xvpffaec@scientiaunknown.non
1
S. Sanjabi
sanjabi@modares.ac.ir
2
M. Naderi
tomkzyzq@scientiaunknown.non
3
H. Zare Bidaki
bgrllpde@scientiaunknown.non
4
Department of Materials Science and Engineering,Sharif University of Technology
Department of Materials Science and Engineering,Tarbiat Modares University
Department of Materials Science and Engineering,Tarbiat Modares University
Department of Materials Science and Engineering,Tarbiat Modares University
Abstract. During recent years, many investigations have been carried out to determine how to select
dierent materials for the making of Micro Electro Mechanical Systems (MEMS) and bio-MEMS. The
NiTi shape memory alloy thin lm has been much regarded as a promising candidate for MEMS due to
its unique shape memory eect and high energy output. In this research, NiTi thin lm was fabricated
using a sputtering technique from separate elemental Ni and Ti targets. The characterizations of the
deposited lms were investigated using dierent analysis techniques, such as Field Emission SEM, DSC,
XRD, electrical resistivity measurement and nanoindentation.
https://scientiairanica.sharif.edu/article_3220_6a16f18d449af70e7dc97f76b16ab175.pdf
NiTi thin lm
Sputtering
Characterization
Shape memory eect