eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2010-10-10
34
2
95
101
10.22099/ijsts.2010.2168
2168
LIGHTLIKE RULED AND REVOLUTION SURFACES IN 3 1
A. ALTIN
1
H. KABADAYI
kabadayi@science.ankara.edu.tr
2
A. SABUNCUOGLU
3
Hacettepe University, Faculty of Science, Department of Mathematics, 06550 Beytepe, Ankara, Turkey
Ankara University, Faculty of Science, Department of Mathematics, 06100 Tandogan, Ankara, Turkey
Ankara University, Faculty of Science, Department of Mathematics, 06100 Tandogan, Ankara, Turkey
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.
http://ijsts.shirazu.ac.ir/article_2168_966d251fe029379c9662704899e31279.pdf
Lightlike surface
lightlike ruled surface
lightlike revolution surface
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2010-10-10
34
2
103
112
10.22099/ijsts.2010.2169
2169
ON THE CASES OF EXPLICIT SOLVABILITY OF A THIRD ORDER PARTIAL DIFFERENTIAL EQUATION
A. MAHER
a_maher69@yahoo.com
1
YE. A. UTKINA
2
Department of Mathematics, University College in Makkah, Pox: 2064, Umm Al-Qura Uni., KSA
Department of Differential Equations, Kazan State University, Russia
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.
http://ijsts.shirazu.ac.ir/article_2169_4c79b0a21011e167ffb9870fa6a0a4ab.pdf
Third order partial differential equation
the Goursat problem
the Riemann function
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2010-10-10
34
2
113
122
10.22099/ijsts.2010.2170
2170
REDUCED DIFFERENTIAL TRANSFORM METHOD FOR SOLVING LINEAR AND NONLINEAR WAVE EQUATIONS
Y. KESKIN
yildiraykeskin@yahoo.com
1
G. OTURANC
2
Department of Mathematics, Science Faculty, Selcuk University, Konya 42003, Turkey
Department of Mathematics, Science Faculty, Selcuk University, Konya 42003, Turkey
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.
http://ijsts.shirazu.ac.ir/article_2170_2f253f0409a3300d7aa942dfd208a1c7.pdf
Reduced differential transform method
wave equation
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2010-10-10
34
2
123
130
10.22099/ijsts.2010.2171
2171
TWO-DIMENSIONAL MAGMA FLOW
A. MEHMOOD
ahmerqau@yahoo.co.uk
1
A. ALI
2
Department of Mathematics (FBAS), International Islamic University Islamabad 44000, Pakistan
Department of Mathematics Quaid-i-Azam University 45320 Islamabad 44000, Pakistan
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
http://ijsts.shirazu.ac.ir/article_2171_81ef0cb3313dcbfedbe0b9308ae0f359.pdf
Magma flow
second-grade fluid
symmetry analysis
exact solution
controlling eruption
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2010-10-10
34
2
131
138
10.22099/ijsts.2010.2172
2172
ELECTRONIC AND STRUCTURAL PROPERTIES OF TIN DIOXIDE IN CUBIC PHASE
A. ARYADOUST
1
SALEHI H.
2
M. FARBOD
3
Department of Physics, Shahid Chamran University, Ahvaz, I. R. of Iran
Department of Physics, Shahid Chamran University, Ahvaz, I. R. of Iran
Department of Physics, Shahid Chamran University, Ahvaz, I. R. of Iran
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.
http://ijsts.shirazu.ac.ir/article_2172_316285dc18231f30cea718418d965276.pdf
Lattice constant
bulk module
ceramic 2 SnO
electronic structure
electronic density distribution
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2010-10-10
34
2
139
150
10.22099/ijsts.2010.2173
2173
DISCRIMINANT ANALYSIS IN AR(p) PLUS DIFFERENT NOISES PROCESSES
B. MANSOURI
1
R. CHINIPARDAZ
chinipardaz_r@scu.ac.ir,
2
G. A. PARHAM
3
Department of Statistics, University of Shahid Chamran, Ahvaz, I. R. Iran
Department of Statistics, University of Shahid Chamran, Ahvaz, I. R. Iran
Department of Statistics, University of Shahid Chamran, Ahvaz, I. R. Iran
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.
http://ijsts.shirazu.ac.ir/article_2173_6dd1a5313b3be6c6f251bcafb9ba2a80.pdf
Log-likelihood discrimination
AR(p) plus noise process
band matrix
pearson-curves
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2010-10-10
34
2
151
160
10.22099/ijsts.2010.2174
2174
JOHNSON AMENABILITY FOR TOPOLOGICAL SEMIGROUPS
M. MAYSAMI SADR
1
A. POURABBAS
arpabbas@aut.ac.ir
2
Department of Mathematics, Institute for Advanced Studies in Basic Sciences, Zanjan, I. R. of Iran
Faculty of Mathematics and Computer Science, Amirkabir University of Technology, 424 Hafez Avenue, Tehran 15914, I. R. of Iran
–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.
http://ijsts.shirazu.ac.ir/article_2174_2990e75e6c1a45f163ad031807c50123.pdf
amenability
crossed homomorphism
topological semigroup
eng
Springer
Iranian Journal of Science and Technology (Sciences)
1028-6276
1028-6276
2010-10-10
34
2
161
167
10.22099/ijsts.2010.2175
2175
APPROXIMATE SOLUTION TO BOUNDARY VALUE PROBLEMS BY THE MODIFIED VIM
M. HEYDARI
1
G. B. LOGHMANI
loghmani@yazduni.ac.ir
2
Department of Mathematics, Yazd University, Yazd, I. R. of Iran
Department of Mathematics, Yazd University, Yazd, I. R. of Iran
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.
http://ijsts.shirazu.ac.ir/article_2175_efbef62a60b71d2f6b575df55bbbc88d.pdf
Variational iteration method
Chebyshev polynomials
boundary value problems