2018-05-25T15:10:10Z
http://ijsts.shirazu.ac.ir/?_action=export&rf=summon&issue=507
Iranian Journal of Science and Technology (Sciences)
Transaction A: Science
1028-6276
1028-6276
2014
38
4
Numerical solution of Reynold’s equation governing noncircular gas bearing system using radial basis function
H.
Rasooli Shooroki
R.
Rashidi Meybodi
S. M.
Karbassi
G. B.
Loghmani
In this paper, the static characteristics of two-lobe, three-lobe and four-lobe noncircular gas journal bearing systems are
studied in detail. The Reynold’s equation governing the noncircular gas bearing systems are analyzed by using Radial Basis
Functions (RBF). The solutions are obtained numerically by solving systems of algebraic equations. The equilibrium position
of the rotor is obtained without using the trial and error method; which is the merit of our method.
Reynold’s equation
noncircular gas bearings
Radial Basis Function
2014
12
22
389
397
http://ijsts.shirazu.ac.ir/article_2555_85c60ec37dc6ac51bf5b56b645f983b6.pdf
Iranian Journal of Science and Technology (Sciences)
Transaction A: Science
1028-6276
1028-6276
2014
38
4
A NSFD scheme for Lotka–Volterra food web model
S.
Zibaei
M.
Namjoo
A nonstandard finite difference (NSFD) scheme has been constructed and analyzed for a mathematical model that describes Lotka–Volterra food web model. This new discrete system has the same stability properties as the continuous model and,on the whole, it preservesthe same local asymptotic stability properties. Linearized stability theory and Schur–Cohn criteria are used for local asymptoticstability of this discrete time model. Numerical results are given to support the results.
Lotka–Volterra
nonstandard finite difference scheme
Stability
2014
12
22
399
414
http://ijsts.shirazu.ac.ir/article_2556_15485c9c4d6bac19c0ab1d9049d4345b.pdf
Iranian Journal of Science and Technology (Sciences)
Transaction A: Science
1028-6276
1028-6276
2014
38
4
E1, E2 and M1 transitions between n=3 levels in magnesium-like tungsten
G.
Günday Konan
S.
Kabakçı
L.
Özdemir
Electric dipole (E1) transitions of 3s-3p and 3p-3d, and electric quadrupole (E2) and magnetic dipole (M1) transitions between fine structure levels of 3s3p and 3p2 in Mg-like tungsten (W62+) have been studied by multiconfiguration Hartree-Fock (MCHF) method. Multielectron ions of high-Z elements are of interest in atomic structure theory. In this work Breit-Pauli relativistic contributions and correlation effects have been considered. The magnesium-like tungsten lines obtained from this work are compared with other theoretical and experimental results.
MCHF method
allowed and forbidden transitions
transition rates
wavelengths
2014
12
22
415
421
http://ijsts.shirazu.ac.ir/article_2557_96a6195489c4d481880b2c0965522a90.pdf
Iranian Journal of Science and Technology (Sciences)
Transaction A: Science
1028-6276
1028-6276
2014
38
4
Analytical solutions for the fractional nonlinear telegraph equation using a modified homotopy perturbation and separation of variables methods
H.
Kheiri
S.
Irandoust-Pakchin
M.
Javidi
In this paper, first a new homotopy perturbation method for solving a fractional order nonlinear telegraph equation is introduced. By applying the proposed method, the nonlinear equation is translated to linear equations for per iteration of homotopy perturbation method. Then, the obtained problems are solved with separation method. In the examples, it is illustrated that the exact solution is obtained in one iteration by conveniently separating source term of equation.
fractional
Telegraph equation
Caputo derivative
homotopy perturbation
separation of variables
Mittag-Leffler
2014
12
22
423
433
http://ijsts.shirazu.ac.ir/article_2558_19fcab0c6999ed50cf09038e2fc4e390.pdf
Iranian Journal of Science and Technology (Sciences)
Transaction A: Science
1028-6276
1028-6276
2014
38
4
A new model for vulnerability assessment of drought in Iran using Percent of Normal Precipitation Index (PNPI)
M.
Masoudi
S.
Hakimi
The Percent of Normal Precipitation Index (PNPI) is a widely used drought index to provide good estimations about the intensity, magnitude and spatial extent of droughts. The objective of this study was analyzing spatial pattern of drought by PNPI index. In this paper, according to the data of 40 stations in Iran, during 1967-2009, the pattern of drought hazard is evaluated. Influenced zone of each station was specified by Thiessen method. An attempt was made to create a new model of drought hazard using GIS. Three criteria for drought were studied and considered to define areas under vulnerability. Drought hazard criteria used in the present model include: maximum severity of drought in the period, trend of drought, and the maximum number of sequential arid years. Both the vulnerability indicator map and also final hazard map are classified into 5 hazard classes of drought: None, slight, moderate, severe and very severe. The final drought vulnerability map was prepared by overlaying three criteria maps in the GIS and the final hazard classes were defined on the basis of hazard scores arrived at by the mean of the main indicators, deploying the new model. The final vulnerability map shows that severe hazard areas (58% of the country) which are observed more in the northwestern, southeastern and central parts of the country are much more widespread than areas under other hazard classes.
Drought
PNPI
GIS
hazard map
Iran
2014
12
22
435
440
http://ijsts.shirazu.ac.ir/article_2559_258f784e4a2bec508730c626b6028437.pdf
Iranian Journal of Science and Technology (Sciences)
Transaction A: Science
1028-6276
1028-6276
2014
38
4
Numerical modeling of the temporal response of back-gated metalsemiconductor- metal photodetector in an equilibrium condition
A.
Habibpour
N.
Das
H. R.
Mashayekhi
We have simulated the carrier concentration and temporal response characteristics of a Back-Gated Metal- Semiconductor-Metal (BG-MSM) photodetector in one dimension as a function of optical pulse position on the active region in an equilibrium condition (without bias voltage to the photodetector). We have adopted a nonlinear ambipolar transport model to simulate the behavior of photo-generated carriers in the active region of the BG-MSM photodetector. From the simulation results, it is observed that for optical pulse positions in the cathode region, the magnitude of the response current is exactly the same but opposite that of the anode region. The response of the photodetector is zero when a pulse is positioned at the center of the active region. This important feature of the device could make it attractive for micro-scale positioning of highly sensitive instruments. Our simulation results agreed well with the experimental results.
BG-MSM Photodetector
equilibrium condition
ambipolar transport
Simulation
2014
12
22
441
444
http://ijsts.shirazu.ac.ir/article_2560_78a43199e054cf68aafc6f8dc1f77ee6.pdf
Iranian Journal of Science and Technology (Sciences)
Transaction A: Science
1028-6276
1028-6276
2014
38
4
Structure of quasi ordered ∗-vector spaces
G. H.
Esslamzadeh
M.
Moazami Goodarzi
F.
Taleghani
Let (𝑋,𝑋+) be a quasi ordered ∗-vector space with order unit, that is, a ∗-vector space 𝑋 with order unite together with a cone 𝑋+⊆𝑋. Our main goal is to find a condition weaker than properness of 𝑋, which suffices for fundamental results of ordered vector space theory to work. We show that having a non-empty state space or equivalently having a non-negative order unit is a suitable replacement for properness of 𝑋+. At first, we examine real vector spaces and then the complex case. Then we apply the results to self adjoint unital subspaces of unital ∗-algebras to find direct and shorter proofs of some of the existing results in the literature.
Quasi ordered ∗-vector space
bounded algebra
quasi operator system
Archimedeanization
2014
12
22
445
453
http://ijsts.shirazu.ac.ir/article_2561_38b0fd0cff8b3aaffb439bd8ee4cc2e6.pdf
Iranian Journal of Science and Technology (Sciences)
Transaction A: Science
1028-6276
1028-6276
2014
38
4
Existence solutions for nonlocal fractional differential equation with nonlinear boundary conditions
N.
Nyamoradi
H.
Alaei Dizaji
In this paper, by employing the Guo-Krasnoselskii fixed point theorem in a cone, we study the existence of positive solutions to the following nonlocal fractional boundary value problems
{ 𝐷0+ 𝛼 𝑢(𝑡) = 𝑓(𝑡, 𝑢(𝑡)), 𝑡 ∈ (0,1), 𝑢𝑡 + 𝑢′(0) = 12 [𝐻1(𝜑𝑢) + ∫ 𝐻2 𝐸(𝑠 𝑢𝑠)𝑑𝑠 , 𝑢1) + 𝑢′(1) = 0, c
where c𝐷0+ 𝛼is the standard Caputo derivative of order 𝛼 1 < 𝛼< 2, 𝐸⊆ (0,1) is some measurable set. We provide conditions on 𝑓 𝐻1, 𝐻2 and 𝜑such that the problem exhibits at least one positive solution.
Cone
fixed point theorem
standard Caputo
derivative
2014
12
22
455
461
http://ijsts.shirazu.ac.ir/article_2562_89c639061537ef57883fe24a62f10c88.pdf
Iranian Journal of Science and Technology (Sciences)
Transaction A: Science
1028-6276
1028-6276
2014
38
4
Friedel–Crafts acylation of aromatic compounds
A. R.
Hajipour
S. H.
Nazemzadeh
H.
Karimi
An efficient method for the Friedel–Crafts acylation of a wide range of aromatic compounds in good to excellent yields under solvent-free conditions, using iron zirconium phosphate (ZPFe) was investigated. The catalyst is easy to prepare and shows interesting catalytic properties. The catalyst was characterized by some instrumental techniques such as XRD, ICP-OES, SEM and TEM. A wide variety of benzene derivatives reacted easily with benzoyl chloride and some of its derivatives to afford the corresponding aromatic ketones in clean and good yields with the para isomer predominating typically using 3mol% of catalyst. The use of inexpensive materials, simple and clean work-up, short reaction times in most cases and good yields are the main advantages of this method. This work introduces a new application of this catalyst, not described in the literature until now. Also, the catalyst can be recovered and reused for three times without a significant loss in its activity and selectivity.
Iron zirconium phosphate
nanoparticles
acylation
Solvent-free
solid catalyst
2014
12
22
463
471
http://ijsts.shirazu.ac.ir/article_2563_12abf4a75c21b1b2ed8a550b3c2bbe21.pdf
Iranian Journal of Science and Technology (Sciences)
Transaction A: Science
1028-6276
1028-6276
2014
38
4
Numerical technique for integro-differential equations arising in oscillating magnetic fields
M.
Ghasemi
In this paper, we propose the Chebyshev wavelet approximation for the numerical solution of a class of integro-differential equation which describes the charged particle motion for certain configurations of oscillating magnetic fields. We show that the Chebyshev approximation transform an integral equation to an explicit system of linear algebraic equations. Illustrative examples are included to demonstrate the validity and applicability of the new technique.
Integro-differential equation
Chebyshev wavelet
charged particle motion
oscillating magnetic field
2014
12
22
473
479
http://ijsts.shirazu.ac.ir/article_2564_460fcd2e3895b13df5b4ce1025525b93.pdf
Iranian Journal of Science and Technology (Sciences)
Transaction A: Science
1028-6276
1028-6276
2014
38
4
Effective workflow for optimization of intelligent well completions
T.
Behrouz
M. R.
Rasaei
R.
Masoudi
Intelligent wells provide the ability for monitoring and control of downhole environment of the wells. Downhole monitoring is achieved through sensors while control is realized with downhole valves. Recovery from intelligent wells can be improved by proper selection of candidate wells/fields and optimizing the number, location and performance of the installed Interval Control Valves. Design criteria, however, suffer from incomplete understanding of the precise determination of these parameters, their interaction and combined effects. Having known the candidate well, we presented a new workflow to optimize the number, location and performance of Interval Control Valves as the main element of intelligent wells. This is a very computationally demanding and time consuming task; therefore a proxy model is developed and applied to speed up the process. Primary evaluations show that optimization of each parameter independently is not the best practice because of their interrelation and combined effects on objective function. An integrated optimization approach is therefore developed in which all the Interval Control Valves’ parameters are optimized together during the process. Considerable improvement in cumulative oil production and control of produced water is achieved by applying this method on real field data.
Intelligent well
Optimization
proxy model
workflow
interval control valve (ICV)
2014
12
22
481
487
http://ijsts.shirazu.ac.ir/article_2565_bf062ef8fb77d7f45954165c1a95757a.pdf
Iranian Journal of Science and Technology (Sciences)
Transaction A: Science
1028-6276
1028-6276
2014
38
4
Synthesis and characterization of new acyclic octadentate ligand and its complexes
F. H. A.
Al-Jeboori
K. k.
Hammud
M. J.
Al-Jeboori
The reaction of an equivalent of 2- mercaptoethyl ammonium chloride with an equivalent of 2,6-diformyl -4- methyl phenol produced monoamine which was reacted with half equivalent of 1,2-diamine ethane to produce ethylene-bis-6-(2-mercapto-ethyl-imine)-methyl -4- methyl phenol [H4L]. The ligand was reacted with metal ions[Cr(III), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II)] at reflux ethanol, under nitrogen at atmosphere. The ligand and derivative 2,6-diformyl-4-methylphenol and metal ion complexes were characterized by elemental microanalysis, IR, UV, (1H, 13C, 1H-1H, 1H-13C)NMR and mass spectroscopies and suggested structures and octahedral for the complexes [Cr, Mn, Co, and Ni] while complexes of [Fe, Zn, Cd, and Hg] suggested tetrahedral geometry and a distorted square planar geometry around copper complex.
Schiff base
metal ion
2-mercaptoethyl ammonium chloride
Synthesis
acyclic octadentate
2014
12
22
489
497
http://ijsts.shirazu.ac.ir/article_2566_7e6b8b7d40182dd87f66611188880820.pdf