PULLBACK CROSSED MODULES OF ALGEBROIDS
M.
ALP
Dumlupinar University, Art and Science Faculty, Mathematics Department, Turkey
author
text
article
2008
eng
In this paper, we present algebroids and crossed modules of algebroids. We also define pullbackcrossed module of algebroids.
Iranian Journal of Science and Technology (Sciences)
Shiraz University
1028-6276
32
v.
1
no.
2008
1
5
http://ijsts.shirazu.ac.ir/article_2234_62c423d9a21fa541e8b88b608b5152fe.pdf
dx.doi.org/10.22099/ijsts.2008.2234
INVESTIGATION ON THE FLUX-BASED TORQUE-RIPPLE BEHAVIOR IN DTC BASED INDUCTION MOTOR DRIVES
Sh
KABOLI
Electrical Engineering Department, Sharif University of Technology, Tehran, I. R. of Iran
author
M. R.
ZOLGHADRI
Electrical Engineering Department, Sharif University of Technology, Tehran, I. R. of Iran
author
S.
HAGHBIN
Electrical Engineering Department, Sharif University of Technology, Tehran, I. R. of Iran
author
P.
ESKANDARI
Electrical Engineering Department, Sharif University of Technology, Tehran, I. R. of Iran
author
text
article
2008
eng
The efficiency of induction motors decreases at light loads. Efficiency optimizer control systemsadjust the motor flux value to achieve the best efficiency in a wide range of load variations. Reduced fluxoperation has some other benefits such as power factor improvement and torque ripple reduction. The latter isan important issue in a direct torque controlled induction motor drive. In this paper, the effect of fluxreference value on the torque ripple of a direct torque controlled induction motor is analyzed. The effect offlux value on torque ripple in a wide range of speed variations is investigated. Simulation and theexperimental results presented justify the validity of the theoretical analysis about torque ripple.
Iranian Journal of Science and Technology (Sciences)
Shiraz University
1028-6276
32
v.
1
no.
2008
7
16
http://ijsts.shirazu.ac.ir/article_2235_67e72585b39a8522188344db21f914fd.pdf
dx.doi.org/10.22099/ijsts.2008.2235
CAPACITY ON FINSLER SPACES
B.
BIDABAD
Faculty of Mathematics and Computer Sciences, Amirkabir University of Technology,
424 Hafez Ave, 15914 Tehran, I. R. of Iran
author
S.
HEDAYATIAN
Faculty of Mathematics and Computer Sciences, Chamran University of Ahvaz, Golestan Bld,
P.O. Box: 61355-83151 Ahvaz, I. R. of Iran
author
text
article
2008
eng
Here, the concept of electric capacity on Finsler spaces is introduced and the fundamentalconformal invariant property is proved, i.e. the capacity of a compact set on a connected non-compact Finslermanifold is conformal invariant. This work enables mathematicians and theoretical physicists to become morefamiliar with the global Finsler geometry and one of its new applications.
Iranian Journal of Science and Technology (Sciences)
Shiraz University
1028-6276
32
v.
1
no.
2008
17
24
http://ijsts.shirazu.ac.ir/article_2237_c853a94eb7e70ca1fcffe2b37e5b1eee.pdf
dx.doi.org/10.22099/ijsts.2008.2237
INTEGRAL CHARACTERIZATIONS FOR TIMELIKE AND SPACELIKE CURVES ON THE LORENTZIAN SPHERE 3 S1
M.
KAZAZ
Department of Mathematics, Faculty of Art and Sciences, University of Celal Bayar,
Muradiye Campus, 45047, Manisa, Turkey
author
H. H.
UGURLU
Gazi University, Gazi Faculty of Education, Department of Secondary Education, Science
and Mathematics Teaching, Mathematics Teaching Program, Ankara, Turkey
author
A.
OZDEMIR
Department of Mathematics, Faculty of Art and Sciences, University of Celal Bayar,
Muradiye Campus, 45047, Manisa, Turkey
author
text
article
2008
eng
V. Dannon showed that spherical curves in E4 can be given by Frenet-like equations, and he thengave an integral characterization for spherical curves in E4 . In this paper, Lorentzian spherical timelike andspacelike curves in the space time 41 R are shown to be given by Frenet-like equations of timelike andspacelike curves in the Euclidean space E3 and the Minkowski 3-space 31 R . Thus, finding an integralcharacterization for a Lorentzian spherical 41 R -timelike and spacelike curve is identical to finding it for E3curves and 31 R -timelike and spacelike curves. In the case of E3 curves, the integral characterizationcoincides with Dannon’s.Let {T, N, B}be the moving Frenet frame along the curve α (s) in the Minkowski space 31 R . Letα (s) be a unit speed C4 -timelike (or spacelike) curve in 31 R so that α '(s) = T . Then, α (s) is a Frenetcurve with curvature κ (s) and torsion τ (s) if and only if there are constant vectors a and b so that(i) { [ ] } 0'( ) ( ) cos ( ) sin ( ) cos ( ) ( ) ( ) ( ) , s T s =κ s a ξ s + b ξ s + ∫ ξ s −ξ δ T δ κ δ dδ T is timelike,(ii) { ( ) } 0'( ) ( ) cosh ( ) ( ) ( ) ( ) s T s =κ s aeξ +be−ξ + ∫ ξ s −ξ δ T δ κ δ dδ , N is timelike,where0( ) ( ) . s ξ s = ∫ τ δ dδ
Iranian Journal of Science and Technology (Sciences)
Shiraz University
1028-6276
32
v.
1
no.
2008
25
31
http://ijsts.shirazu.ac.ir/article_2238_9ccf89393e0c615c0234b48509b20d4e.pdf
dx.doi.org/10.22099/ijsts.2008.2238
DIRAC STRUCTURES
A.
SHAFIEI DEH ABAD
School of Mathematics, Statistics and Computer Science, University of Tehran, Tehran, I. R. of Iran
author
text
article
2008
eng
In this paper we introduce the concept of Dirac structures on (Hermitian) modules and vectorbundles and deduce some of their properties. Among other things we prove that there is a one to onecorrespondence between the set of all Dirac structures on a (Hermitian) module and the group of allautomorphisms of the module. This correspondence enables us to represent Dirac structures on (Hermitian)modules and on vector bundles in a very suitable form and define induced Dirac structures in a natural way.
Iranian Journal of Science and Technology (Sciences)
Shiraz University
1028-6276
32
v.
1
no.
2008
33
44
http://ijsts.shirazu.ac.ir/article_2239_ec8e645e2e54512fcf6f5038521f36fe.pdf
dx.doi.org/10.22099/ijsts.2008.2239
ON ENERGY DECAY OF AN N-DIMENSIONAL THERMOELASTICITY SYSTEM WITH A NONLINEAR WEAK DAMPING
F.
TAHAMTANI
Department of Mathematics, Shiraz University, Shiraz, I. R. of Iran
author
text
article
2008
eng
We study the exponential decay of global solution for an n-dimensional thermo-elasticity systemin a bounded domain of ℜn . By using the multiplier technique and constructing an energy functional welladapted to the system, the exponential decay is proved.
Iranian Journal of Science and Technology (Sciences)
Shiraz University
1028-6276
32
v.
1
no.
2008
45
51
http://ijsts.shirazu.ac.ir/article_2240_6be2e046e60631ea1bf828a2a5179ccd.pdf
dx.doi.org/10.22099/ijsts.2008.2240
CONFORMAL VECTOR FIELDS ON TANGENT BUNDLE WITH A SPECIAL LIFT FINSLER METRIC*
E.
PEYGHAN
Department of Mathematics, Faculty of Science, University of Arak, Arak, I. R. of Iran
author
A.
RAZAVI
Department of Mathematics and Computer Science, Amirkabir University, Tehran, I. R. of Iran
author
A.
HEYDARI
Faculty of Science, Tarbiatmodares University, Tehran, I. R. of Iran
author
text
article
2008
eng
On a Finsler manifold, we define conformal vector fields and their complete lifts and prove that incertain conditions they are homothetic.
Iranian Journal of Science and Technology (Sciences)
Shiraz University
1028-6276
32
v.
1
no.
2008
53
59
http://ijsts.shirazu.ac.ir/article_2242_a7a4b6fb2c6283dfb292f9e29ed1cc7f.pdf
dx.doi.org/10.22099/ijsts.2008.2242
THE STRUCTURE OF DERIVATIONS FROM A FULL MATRIX ALGEBRA INTO ITS DUAL
R.
ALIZADEH
Department of Mathematics, Shahed University, P. O. Box 18151-159, Tehran, I. R. of Iran
author
H.
ESSLAMZADEH
Department of Mathematics, Shiraz University, Shiraz 71454, I. R. of Iran
author
text
article
2008
eng
Let A be a unital algebra over a field of characteristic zero. We show that every derivation from( ) n M A into its dual ( ) n M A ∗ is the sum of an inner derivation and a derivation induced by a derivationfrom A into A∗
Iranian Journal of Science and Technology (Sciences)
Shiraz University
1028-6276
32
v.
1
no.
2008
61
64
http://ijsts.shirazu.ac.ir/article_2243_75889e97656d745af5ba0a1ac3c67c89.pdf
dx.doi.org/10.22099/ijsts.2008.2243
α − SEPARABLE AND O-TOPOLOGICAL GROUP
K.
HAGHNEJAD AZAR
Department of Mathematics, Mohghegh Ardabili University, Ardabil, I. R. of Iran
author
A.
RIAZI
Faculty of Mathematics and Computer Science, Amir Kabir University Tehran, I. R. of Iran
author
text
article
2008
eng
We introduce some new concepts of topological spaces which say α − separable topologicalspace and O-topological group, α − first axiom, α − second axiom, and we find some relations betweenthem with some applications in normed spaces.
Iranian Journal of Science and Technology (Sciences)
Shiraz University
1028-6276
32
v.
1
no.
2008
65
70
http://ijsts.shirazu.ac.ir/article_2244_96cf814894c4986d8503ec748d4bbf73.pdf
dx.doi.org/10.22099/ijsts.2008.2244
ON THE DISTRIBUTION OF Z-SCORES
J.
BEHBOODIAN
Department of Mathematics, Islamic Azad University, Shiraz, I. R. of Iran
author
A.
ASGHARZADEH
Department of Statistics, Faculty of Basic Sciences, Mazandaran University, Babolsar, I. R. of Iran
author
text
article
2008
eng
Let X ,..., Xn 1 be a random sample from a distribution with sample mean X and samplevariance S 2. In this paper we consider certain very general properties of the so-called “Z-scores”X X S i n i ( − )/ : = 1,...., . A representation theorem is then given for Z-scores obtained from an underlyingnormal population, together with a theorem for their limiting distribution as the sample size tends to infinity.Finally, two applications involving grading and testing for an outlier are presented.
Iranian Journal of Science and Technology (Sciences)
Shiraz University
1028-6276
32
v.
1
no.
2008
71
78
http://ijsts.shirazu.ac.ir/article_2245_7c4086e2bf5cb1aaec28c2c0824b1b6e.pdf
dx.doi.org/10.22099/ijsts.2008.2245