Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
34
2
2010
10
10
LIGHTLIKE RULED AND REVOLUTION SURFACES IN 3 1
95
101
EN
A.
ALTIN
Hacettepe University, Faculty of Science, Department of Mathematics, 06550 Beytepe, Ankara, Turkey
H.
KABADAYI
Ankara University, Faculty of Science, Department of Mathematics, 06100 Tandogan, Ankara, Turkey
kabadayi@science.ankara.edu.tr
A.
SABUNCUOGLU
Ankara University, Faculty of Science, Department of Mathematics, 06100 Tandogan, Ankara, Turkey
10.22099/ijsts.2010.2168
In this paper lightlike ruled surfaces in 3 1=(3,-dx2+dy2+dz2) are studied with respect to whetherruling curves are spacelike or null. It is seen that, in the first case the Gaussian curvature of the ruled surfacesvanishes. In the second case the Gaussian curvature of the ruled surfaces are negative. In the second caselightlike ruled surfaces are totally umbilical. Furthermore, lightlike surfaces of revolution are shown to beonly cones, and the second type lightlike ruled surface.
Lightlike surface,lightlike ruled surface,lightlike revolution surface
http://ijsts.shirazu.ac.ir/article_2168.html
http://ijsts.shirazu.ac.ir/article_2168_966d251fe029379c9662704899e31279.pdf
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
34
2
2010
10
10
ON THE CASES OF EXPLICIT SOLVABILITY OF A THIRD ORDER PARTIAL DIFFERENTIAL EQUATION
103
112
EN
A.
MAHER
Department of Mathematics, University College in Makkah, Pox: 2064, Umm Al-Qura Uni., KSA
a_maher69@yahoo.com
YE. A.
UTKINA
Department of Differential Equations, Kazan State University, Russia
10.22099/ijsts.2010.2169
In this paper, the Goursat problem of a third order equation on cases of explicit solvability isinvestigated, with the help of the Riemann function. Some results and one theorem are given concerning theexistence and uniqueness for the solution of the suggested problem.
Third order partial differential equation,the Goursat problem,the Riemann function
http://ijsts.shirazu.ac.ir/article_2169.html
http://ijsts.shirazu.ac.ir/article_2169_4c79b0a21011e167ffb9870fa6a0a4ab.pdf
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
34
2
2010
10
10
REDUCED DIFFERENTIAL TRANSFORM METHOD FOR SOLVING LINEAR AND NONLINEAR WAVE EQUATIONS
113
122
EN
Y.
KESKIN
Department of Mathematics, Science Faculty, Selcuk University, Konya 42003, Turkey
yildiraykeskin@yahoo.com
G.
OTURANC
Department of Mathematics, Science Faculty, Selcuk University, Konya 42003, Turkey
10.22099/ijsts.2010.2170
Reduced differential transform method (RDTM) is applied to various wave equations. To assessthe accuracy of the solutions, we compare the results with the exact solutions and variational iteration method.The results reveal that the RDTM is very effective, convenient and quite accurate to systems of nonlinearequations.
Reduced differential transform method,wave equation
http://ijsts.shirazu.ac.ir/article_2170.html
http://ijsts.shirazu.ac.ir/article_2170_2f253f0409a3300d7aa942dfd208a1c7.pdf
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
34
2
2010
10
10
TWO-DIMENSIONAL MAGMA FLOW
123
130
EN
A.
MEHMOOD
Department of Mathematics (FBAS), International Islamic University Islamabad 44000, Pakistan
ahmerqau@yahoo.co.uk
A.
ALI
Department of Mathematics Quaid-i-Azam University 45320 Islamabad 44000, Pakistan
10.22099/ijsts.2010.2171
Exact solution for steady two-dimensional flow of an incompressible magma is obtained. Themagmatic flow is studied by considering the magma as a second grade fluid. The governing partialdifferential equations are transformed to ordinary differential equations by symmetry transformations. Resultsare discussed through graphs to understand the rheology of the flowing magma
Magma flow,second-grade fluid,symmetry analysis,exact solution,controlling eruption
http://ijsts.shirazu.ac.ir/article_2171.html
http://ijsts.shirazu.ac.ir/article_2171_81ef0cb3313dcbfedbe0b9308ae0f359.pdf
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
34
2
2010
10
10
ELECTRONIC AND STRUCTURAL PROPERTIES OF TIN DIOXIDE IN CUBIC PHASE
131
138
EN
A.
ARYADOUST
Department of Physics, Shahid Chamran University, Ahvaz, I. R. of Iran
SALEHI
H.
Department of Physics, Shahid Chamran University, Ahvaz, I. R. of Iran
M.
FARBOD
Department of Physics, Shahid Chamran University, Ahvaz, I. R. of Iran
10.22099/ijsts.2010.2172
The electronic structure, energy band structure and electronic density of 2 SnO ceramic in cubicphase have been investigated using first principle full potential-linearized augmented plane wave (FP-LAPW)method within density functional theory (DFT). Local density approximation (LDA) and the generalizedgradient approximation (GGA), which are based on exchange- correlation energy optimization were used.The band gap was 2.2 eV at point in the Brillouin zone within our approach. Calculations of the bandstructure and electronic structure of 2 SnO were in a good agreement with the previous experimental andtheoretical results with different approximations. Moreover, electronic density map shows that the bondingbetween Sn and O atoms is ionic.
Lattice constant,bulk module,ceramic 2 SnO,electronic structure,electronic density distribution
http://ijsts.shirazu.ac.ir/article_2172.html
http://ijsts.shirazu.ac.ir/article_2172_316285dc18231f30cea718418d965276.pdf
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
34
2
2010
10
10
DISCRIMINANT ANALYSIS IN AR(p) PLUS DIFFERENT NOISES PROCESSES
139
150
EN
B.
MANSOURI
Department of Statistics, University of Shahid Chamran, Ahvaz, I. R. Iran
R.
CHINIPARDAZ
Department of Statistics, University of Shahid Chamran, Ahvaz, I. R. Iran
chinipardaz_r@scu.ac.ir,
G. A.
PARHAM
Department of Statistics, University of Shahid Chamran, Ahvaz, I. R. Iran
10.22099/ijsts.2010.2173
The problem of discrimination between two stationary AR(p) plus noise processes is consideredwhen the noise process are different in two models. The discrimination rule leads to a quadratic form withcumbersome matrices. An approximate and analytic form is given to distribution of the discriminant. Thesimulation study has been used to show the performance of discrimination rule. The cumulants ofdiscriminant function are obtained and show them to be very close to the true values given in literature.
Log-likelihood discrimination,AR(p) plus noise process,band matrix,pearson-curves
http://ijsts.shirazu.ac.ir/article_2173.html
http://ijsts.shirazu.ac.ir/article_2173_6dd1a5313b3be6c6f251bcafb9ba2a80.pdf
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
34
2
2010
10
10
JOHNSON AMENABILITY FOR TOPOLOGICAL SEMIGROUPS
151
160
EN
M.
MAYSAMI SADR
Department of Mathematics, Institute for Advanced Studies in Basic Sciences, Zanjan, I. R. of Iran
A.
POURABBAS
Faculty of Mathematics and Computer Science, Amirkabir University of
Technology, 424 Hafez Avenue, Tehran 15914, I. R. of Iran
arpabbas@aut.ac.ir
10.22099/ijsts.2010.2174
–A notion of amenability for topological semigroups is introduced. A topological semigroup S iscalled Johnson amenable if for every Banach S -bimodule E , every bounded crossed homomorphism fromS to E* is principal. In this paper it is shown that a discrete semigroup S is Johnson amenable if and only if1(S) is an amenable Banach algebra. Also, we show that if a topological semigroup S is Johnson amenable,then it is amenable, but the converse is not true.
amenability,crossed homomorphism,topological semigroup
http://ijsts.shirazu.ac.ir/article_2174.html
http://ijsts.shirazu.ac.ir/article_2174_2990e75e6c1a45f163ad031807c50123.pdf
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
34
2
2010
10
10
APPROXIMATE SOLUTION TO BOUNDARY VALUE PROBLEMS BY THE MODIFIED VIM
161
167
EN
M.
HEYDARI
Department of Mathematics, Yazd University, Yazd, I. R. of Iran
G. B.
LOGHMANI
Department of Mathematics, Yazd University, Yazd, I. R. of Iran
loghmani@yazduni.ac.ir
10.22099/ijsts.2010.2175
This paper presents an efficient modification of the variational iteration method for solvingboundary value problems using the chebyshev polynomials. The proposed method can be applied to linearand nonlinear models. The scheme is tested for some examples and the obtained results demonstrate thereliability and efficiency of the proposed method.
Variational iteration method,Chebyshev polynomials,boundary value problems
http://ijsts.shirazu.ac.ir/article_2175.html
http://ijsts.shirazu.ac.ir/article_2175_efbef62a60b71d2f6b575df55bbbc88d.pdf