SpringerIranian Journal of Science and Technology (Sciences)1028-627634220101010LIGHTLIKE RULED AND REVOLUTION SURFACES IN 3 195101216810.22099/ijsts.2010.2168ENA. ALTINHacettepe University, Faculty of Science, Department of Mathematics, 06550 Beytepe, Ankara, TurkeyH. KABADAYIAnkara University, Faculty of Science, Department of Mathematics, 06100 Tandogan, Ankara, TurkeyA. SABUNCUOGLUAnkara University, Faculty of Science, Department of Mathematics, 06100 Tandogan, Ankara, TurkeyJournal Article20080930In this paper lightlike ruled surfaces in 3 1=(3,-dx2+dy2+dz2) are studied with respect to whether<br />ruling curves are spacelike or null. It is seen that, in the first case the Gaussian curvature of the ruled surfaces<br />vanishes. In the second case the Gaussian curvature of the ruled surfaces are negative. In the second case<br />lightlike ruled surfaces are totally umbilical. Furthermore, lightlike surfaces of revolution are shown to be<br />only cones, and the second type lightlike ruled surface.SpringerIranian Journal of Science and Technology (Sciences)1028-627634220101010ON THE CASES OF EXPLICIT SOLVABILITY OF A THIRD ORDER PARTIAL DIFFERENTIAL EQUATION103112216910.22099/ijsts.2010.2169ENA. MAHERDepartment of Mathematics, University College in Makkah, Pox: 2064, Umm Al-Qura Uni., KSAYE. A. UTKINADepartment of Differential Equations, Kazan State University, RussiaJournal Article20100618In this paper, the Goursat problem of a third order equation on cases of explicit solvability is<br />investigated, with the help of the Riemann function. Some results and one theorem are given concerning the<br />existence and uniqueness for the solution of the suggested problem.SpringerIranian Journal of Science and Technology (Sciences)1028-627634220101010REDUCED DIFFERENTIAL TRANSFORM METHOD FOR SOLVING LINEAR AND NONLINEAR WAVE EQUATIONS113122217010.22099/ijsts.2010.2170ENY. KESKINDepartment of Mathematics, Science Faculty, Selcuk University, Konya 42003, TurkeyG. OTURANCDepartment of Mathematics, Science Faculty, Selcuk University, Konya 42003, TurkeyJournal Article20100421Reduced differential transform method (RDTM) is applied to various wave equations. To assess<br />the accuracy of the solutions, we compare the results with the exact solutions and variational iteration method.<br />The results reveal that the RDTM is very effective, convenient and quite accurate to systems of nonlinear<br />equations.SpringerIranian Journal of Science and Technology (Sciences)1028-627634220101010TWO-DIMENSIONAL MAGMA FLOW123130217110.22099/ijsts.2010.2171ENA. MEHMOODDepartment of Mathematics (FBAS), International Islamic University Islamabad 44000, PakistanA. ALIDepartment of Mathematics Quaid-i-Azam University 45320 Islamabad 44000, PakistanJournal Article20100615Exact solution for steady two-dimensional flow of an incompressible magma is obtained. The<br />magmatic flow is studied by considering the magma as a second grade fluid. The governing partial<br />differential equations are transformed to ordinary differential equations by symmetry transformations. Results<br />are discussed through graphs to understand the rheology of the flowing magmaSpringerIranian Journal of Science and Technology (Sciences)1028-627634220101010ELECTRONIC AND STRUCTURAL PROPERTIES OF TIN DIOXIDE IN CUBIC PHASE131138217210.22099/ijsts.2010.2172ENA. ARYADOUSTDepartment of Physics, Shahid Chamran University, Ahvaz, I. R. of IranSALEHI H.Department of Physics, Shahid Chamran University, Ahvaz, I. R. of IranM. FARBODDepartment of Physics, Shahid Chamran University, Ahvaz, I. R. of IranJournal Article20090831The electronic structure, energy band structure and electronic density of 2 SnO ceramic in cubic<br />phase have been investigated using first principle full potential-linearized augmented plane wave (FP-LAPW)<br />method within density functional theory (DFT). Local density approximation (LDA) and the generalized<br />gradient approximation (GGA), which are based on exchange- correlation energy optimization were used.<br />The band gap was 2.2 eV at point in the Brillouin zone within our approach. Calculations of the band<br />structure and electronic structure of 2 SnO were in a good agreement with the previous experimental and<br />theoretical results with different approximations. Moreover, electronic density map shows that the bonding<br />between Sn and O atoms is ionic.SpringerIranian Journal of Science and Technology (Sciences)1028-627634220101010DISCRIMINANT ANALYSIS IN AR(p) PLUS DIFFERENT NOISES PROCESSES139150217310.22099/ijsts.2010.2173ENB. MANSOURIDepartment of Statistics, University of Shahid Chamran, Ahvaz, I. R. IranR. CHINIPARDAZDepartment of Statistics, University of Shahid Chamran, Ahvaz, I. R. IranG. A. PARHAMDepartment of Statistics, University of Shahid Chamran, Ahvaz, I. R. IranJournal Article20100405The problem of discrimination between two stationary AR(p) plus noise processes is considered<br />when the noise process are different in two models. The discrimination rule leads to a quadratic form with<br />cumbersome matrices. An approximate and analytic form is given to distribution of the discriminant. The<br />simulation study has been used to show the performance of discrimination rule. The cumulants of<br />discriminant function are obtained and show them to be very close to the true values given in literature.SpringerIranian Journal of Science and Technology (Sciences)1028-627634220101010JOHNSON AMENABILITY FOR TOPOLOGICAL SEMIGROUPS151160217410.22099/ijsts.2010.2174ENM. MAYSAMI SADRDepartment of Mathematics, Institute for Advanced Studies in Basic Sciences, Zanjan, I. R. of IranA. POURABBASFaculty of Mathematics and Computer Science, Amirkabir University of
Technology, 424 Hafez Avenue, Tehran 15914, I. R. of IranJournal Article20090916–A notion of amenability for topological semigroups is introduced. A topological semigroup S is<br />called Johnson amenable if for every Banach S -bimodule E , every bounded crossed homomorphism from<br />S to E* is principal. In this paper it is shown that a discrete semigroup S is Johnson amenable if and only if<br />1(S) is an amenable Banach algebra. Also, we show that if a topological semigroup S is Johnson amenable,<br />then it is amenable, but the converse is not true.SpringerIranian Journal of Science and Technology (Sciences)1028-627634220101010APPROXIMATE SOLUTION TO BOUNDARY VALUE PROBLEMS BY THE MODIFIED VIM161167217510.22099/ijsts.2010.2175ENM. HEYDARIDepartment of Mathematics, Yazd University, Yazd, I. R. of IranG. B. LOGHMANIDepartment of Mathematics, Yazd University, Yazd, I. R. of IranJournal Article20090602This paper presents an efficient modification of the variational iteration method for solving<br />boundary value problems using the chebyshev polynomials. The proposed method can be applied to linear<br />and nonlinear models. The scheme is tested for some examples and the obtained results demonstrate the<br />reliability and efficiency of the proposed method.