oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2017 ( 2 )

2016 ( 1 )

2015 ( 12 )

2014 ( 11 )

Custom range...

Search Results: 1 - 10 of 154 matches for " Asadollah Farhadi "
All listed articles are free for downloading (OA Articles)
Page 1 /154
Display every page Item
Synthesis of Some Hexahydroquinazolinones Using K3AlF6(Al2O3/KF) as an Efficient Catalyst in Some Hexahydroquinazolinone Derivatives  [PDF]
Masoumeh Mehrabi, Asadollah Farhadi, Alireza Kiassat
International Journal of Organic Chemistry (IJOC) , 2017, DOI: 10.4236/ijoc.2017.73018
Abstract: A protocol for the synthesis of some 4-Aryl-1,3,4,6,7,8-hexahydroquinazolin-2,5(1H,6H)-diones (HHQs) was developed by means of a three-component condensation reaction of an aromatic aldehyde, 1,3-cylohexadione and urea in the presence of K3AlF6 (Al2O3/KF) as catalyst. This reaction is carried out under different conditions including 1) solvent free; 2) reflux in acetonitrile; 3) reflux in ethanol; 4) reflux in chloroform; and 5) reflux in water. In all conditions, the desired products are obtained in high yields after relatively short reaction times. Nevertheless, the reactions proceed faster and in higher yields when they were carried out in acetonitrile. This adopted protocol for some Biginelli-type products has offered the advantages of reusability of the catalyst, high yields and ease of separation of pure products. Furthermore, the catalyst is easily prepared, stabilized and efficiently used under reaction conditions.
Introduction to Secure PRNGs  [PDF]
Majid Babaei, Mohsen Farhadi
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2011, DOI: 10.4236/ijcns.2011.410074
Abstract: Pseudo-Random Number Generators (PRNGs) are required for generating secret keys in cryptographic algorithms, generating sequences of packet in Network simulations (workload generators) and other applications in various fields. In this paper we will discuss a list of some requirements for generating a reliable random sequence and then will present some PRNG methods which are based on combinational chaotic logistic map. In the final section after a brief introduction to two statistical test packets, TestU01 and NIST suite tests, the PRNG methods which are presented in the fourth section will be appraised under these test packets and the results will be reported.
New a priori estimates for semistable solutions of semilinear elliptic equations
Asadollah Aghajani
Mathematics , 2015,
Abstract: We consider the semilinear elliptic equation $-L u = f(u)$ in a general smooth bounded domain $\Omega \subset R^{n}$ with zero Dirichlet boundary condition, where $L$ is a uniformly elliptic operator and $f$ is a $C^{2}$ positive, nondecreasing and convex function in $[0,\infty)$ such that $\frac{f(t)}{t}\rightarrow\infty$ as $t\rightarrow\infty$. We prove that if $u$ is a positive semistable solution then for every $0\leq\beta<1$ we have $$f(u)\int_{0}^{u}f(t)f"(t)~e^{2\beta\int_{0}^{t}\sqrt{\frac{f"(s)}{f(s)}}ds}~dt\in L^{1}(\Omega),$$ by a constant independent of $u$. As we shall see, a large number of results in the literature concerning a priori bounds are immediate consequences of this estimate. In particular, among other results, we establish a priori $L^{\infty}$ bound in dimensions $n\leq 9$, under the extra assumption that $\limsup_{t\rightarrow\infty} \frac{f(t)f"(t)}{f'(t)^{2}} < \frac{2}{9-2\sqrt{14}}\cong 1.318$. Also, we establish a priori $L^{\infty}$ bound when $n\leq 5$ under the very weak assumption that, for some $\epsilon>0$, $\liminf_{t\rightarrow\infty} \frac{(tf(t))^{2-\epsilon}}{f'(t)} > 0$ or $\liminf_{t\rightarrow\infty} \frac{t^{2}f(t)f"(t)}{f'(t)^{\frac{3}{2}+\epsilon}} > 0$.
Regularity of extremal solutions of semilinear elliptic problems with non-convex nonlinearities on general domains
Asadollah Aghajani
Mathematics , 2015,
Abstract: We consider the semilinear elliptic equation $-\Delta u =\lambda f(u)$ in a smooth bounded domain $\Omega$ of $R^{n}$ with Dirichielt boundary condition, where $f$ is a $C^{1}$ positive and nondeccreasing function in $[0,\infty)$ such that $\frac{f(t)}{t}\rightarrow\infty$ as $t\rightarrow\infty$. When $\Omega$ is an arbitrary domain and $f$ is not necessarily convex, the boundedness of the extremal solution $u^{*}$ is known only for $n= 2$, established by X. Cabr\'{e} \cite{C1}. In this paper, we prove this for higher dimensions depending on the nonlinearity $f$. In particular, we prove that if $$\frac{1}{2}<\beta_{-}:=\liminf_{t\rightarrow\infty} \frac{f'(t)F(t)}{f(t)^{2}}\leq \beta_{+}:=\limsup_{t\rightarrow\infty} \frac{f'(t)F(t)}{f(t)^{2}}<\infty$$ where $F(t)=\int_{0}^{t}f(s)ds$, then $u^{*}\in L^{\infty}(\Omega)$, for $n\leq 6$. Also, if $\beta_{-}=\beta_{+}>\frac{1}{2}$ or $\frac{1}{2}<\beta_{-}\leq\beta_{+}<\frac{7}{10}$, then $u^{*}\in L^{\infty}(\Omega)$, for $n\leq 9$. Moreover, if $\beta_{-}>\frac{1}{2}$ then $u^{*}\in H^{1}_{0}(\Omega)$ for $n\geq 2$.
Cryptographic PRNG Based on Combination of LFSR and Chaotic Logistic Map  [PDF]
Hamed Rahimov, Majid Babaei, Mohsen Farhadi
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.212217
Abstract: The random sequence generated by linear feedback shift register can’t meet the demand of unpredictability for secure paradigms. A combination logistic chaotic equation improves the linear property of LFSR and constructs a novel random sequence generator with longer period and complex architecture. We present the detailed result of the statistical testing on generated bit sequences, done by very strict tests of randomness: the NIST suite tests, to detect the specific characteristic expected of truly random sequences. The results of NIST’s statistical tests show that our proposed method for generating random numbers has more efficient performance.
Intragenomic diversity and geographical adaptability of diploid cotton species revealed by cytogenetic studies
A Omran, A Asadollah
African Journal of Biotechnology , 2007,
Abstract: Cotton is one of the most important crops in Iran, and is cultivated in different regions of the country. Gossypium herbaceum is one of the A-genome cottons, which is a potentially important genetic resource for cotton breeding programs. Collecting native cultivars of this species growing in different regions is a vital step in broadening variability of the gene pool. The G. herbaceum is one of the two cultivated species under cultivation in Iran, which is specifically adapted to a given environment and includes more than 40 ecotypes, named as landrace cottons. The present paper reports the intragenomic characteristics analysis of 42 G. herbaceum cultivars in the cotton genebank using cytological methods. The karyological studies showed variations within the species in the size of chromosome, chromosome volume and karyotype formulae. All cultivars possessed 2n=26 chromosome, but varied with regard to number of SAT-chromosomes (ranging from 1 to 3) and the chromosomes carrying secondary constructions. Karyotypes were of symmetrical type, having small chromosomes. Analysis of variance revealed significant differences between the cultivars as well as the chromosomes. Cluster analysis could group the cultivars in four distinct clusters. The present study indicates genomic differences among diploid G. herbaceum cultivars, which can be used in cotton hybridization programs in Iran or other countries.
Multiplicity of positive solutions for quasilinear elliptic p-Laplacian systems
Asadollah Aghajani,Jamileh Shamshiri
Electronic Journal of Differential Equations , 2012,
Abstract: We study the existence and multiplicity of solutions to the elliptic system $$displaylines{ -hbox{div}(| abla u|^{p-2} abla u)+m_1(x)|u|^{p-2}u =lambda g(x,u) quad xin Omega,cr -hbox{div}(| abla v|^{p-2} abla v)+m_2(x)|v|^{p-2}v=mu h(x,v) quad xin Omega,cr | abla u|^{p-2}frac{partial u}{partial n}=f_u(x,u,v),quad | abla v|^{p-2}frac{partial v}{partial n}=f_v(x,u,v), }$$ where $Omegasubset mathbb{{R}}^N$ is a bounded and smooth domain. Using fibering maps and extracting Palais-Smale sequences in the Nehari manifold, we prove the existence of at least two distinct nontrivial nonnegative solutions.
One-pot synthesis of polyhydropyridine derivatives via Hantzsch four component condensation in water medium: Use of a recyclable Lewis acid [Ce(SO4)2.4H2O] catalyst
Elaheh Mosaddegh,Asadollah Hassankhani
Bulletin of the Chemical Society of Ethiopia , 2012,
Abstract: An efficient and eco-friendly method for the synthesis of polyhydroquinoline derivatives using Ce(SO4)2.4H2O as mild and heterogeneous Lewis acid catalyst via the Hantzsch reaction in very short reaction time is reported. A mixture of an appropriate aldehyde, dimedone, ethyl acetoacetate and malononitrile in the presence of the Ce(SO4)2.4H2O at reflux conditions in water based media resulted in good to excellent yields of the corresponding products. The catalyst can be used as selective for some aromatic aldehydes in the reaction conditions.DOI: http://dx.doi.org/10.4314/bcse.v26i3.16
Generalized Projectively Symmetric Spaces
Dariush Latifi,Asadollah Razavi
Geometry , 2013, DOI: 10.1155/2013/292691
Abstract: We study generalized projectively symmetric spaces. We first study some geometric properties of projectively symmetric spaces and prove that any such space is projectively homogeneous and under certain conditions the projective curvature tensor vanishes. Then we prove that given any regular projective s-space ( , ), there exists a projectively related connection , such that ( , ) is an affine s-manifold. 1. Introduction Affine and Riemannian s-manifolds were first defined in [1] following the introduction of generalized Riemannian symmetric spaces in [2]. They form a more general class than the symmetric spaces of E. Cartan. More details about generalized symmetric spaces can be found in the monograph [3]. Let be a connected manifold with an affine connection , and let be the Lie transformation group of all affine transformation of . An affine transformation will be called an affine symmetry at a point if is an isolated fixed point of . An affine manifold will be called an affine s-manifold if there is a differentiable mapping , such that for each , is an affine symmetry at . In [4] Podestà introduced the notion of a projectively symmetric space in the following sense. Let be a connected manifold with an affine torsion free connection on its tangent bundle; is said to be projectively symmetric if for every point of there is an involutive projective transformation of fixing and whose differential at is . The assignment of a symmetry at each point of can be viewed as a map , and can be topologised, so that it is a Lie transformation group. In the above definition, however, no further assumption on is made; even continuity is not assumed. In this paper we define and state prerequisite results on projective structures and define projective symmetric spaces due toPodestà. Then we generalize them to define projective s-manifolds as manifolds together with more general symmetries and consider the cases where they are essential or inessential. A projective s-manifold is called inessential if it is projectively equivalent to an affine s-manifold and essential otherwise. We prove that these spaces are naturally homogeneous, and moreover under certain conditions the projective curvature tensor vanishes. Later we define regular projective s-manifolds and prove that they are inessential. 2. Preliminaries Let be a connected real manifold whose tangent bundle is endowed with an affine torsion free connection . We recall that a diffeomorphism of is said to be projective transformation if maps geodesics into geodesics when the parametrization is disregarded [5];
A symmetric Finsler space with Chern connection
Dariush Latifi,Asadollah Razavi
Mathematics , 2007,
Abstract: We define a symmetry for a Finsler space with Chern connection and investigate its implementation and properties and find a relation between them and flag curvature.
Page 1 /154
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.