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Search Results: 1 - 10 of 2097 matches for " Alireza Ataei "
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A QMR-Type Algorithm for Drazin-Inverse Solution of Singular Nonsymmetric Linear Systems  [PDF]
Alireza Ataei
Advances in Linear Algebra & Matrix Theory (ALAMT) , 2016, DOI: 10.4236/alamt.2016.64011
Abstract: In this paper, we propose DQMR algorithm for the Drazin-inverse solution of consistent or inconsistent linear systems of the form Ax=b where \"\"?is a?singular and in general non-hermitian matrix that has an arbitrary index. DQMR algorithm for singular systems is analogous to QMR algorithm for non-singular systems. We compare this algorithm with DGMRES by numerical experiments.
Improved Qrginv Algorithm for Computing Moore-Penrose Inverse Matrices
Alireza Ataei
ISRN Applied Mathematics , 2014, DOI: 10.1155/2014/641706
Abstract: Katsikis et al. presented a computational method in order to calculate the Moore-Penrose inverse of an arbitrary matrix (including singular and rectangular) (2011). In this paper, an improved version of this method is presented for computing the pseudo inverse of an real matrix A with rank . Numerical experiments show that the resulting pseudoinverse matrix is reasonably accurate and its computation time is significantly less than that obtained by Katsikis et al. 1. Introduction Let denote the set of all matrices over the field of real numbers, . The symbols , rank( ) will stand for the transpose and rank of , respectively. For a matrix , the Moore-Penrose inverse of , denoted by , is the unique matrix satisfying the following equations:(i) , (ii) , (iii) , (iv) . A lot of works concerning generalized inverses have been carried out, in finite and infinite dimensions (e.g., [1–3]). There are several methods for computing the Moore-Penrose inverse matrix [2, 4–8]. In a recent article [9], an improved method for the computation of the Moore-Penrose inverse matrix provided. In this paper, we aim to improve their method so that it can be used for any kind of matrices, square or rectangular, full rank or not. The numerical examples show that our method is competitive in terms of accuracy and is much faster than the commonly used methods and can also be used for large sparse matrices. This paper is organized as follows. In Section 2 the improved version of this method is presented for computing the pseudoinverse of an real matrix with rank . In Section 3, the numerical results of some test matrices are given. Section 4 is devoted to the concluding remarks. 2. Improved Qrginv Method (IMqrginv) In [9], a method (qrginv) for computing the Moore-Penrose inverse of an arbitrary matrix was presented. They made use of the QR-factorization, as well as an algorithm based on a known reverse order law for generalized inverse matrices, and also they apply a method (ginv), presented in [4], based on a full rank Cholesky factorization of possibly singular symmetric positive matrices. In the current paper, we improved qrginv algorithm using the QR-factorization by Gram-Schmidt orthonormalization (GSO) and Theorem 1 for faster computing Moore-Penrose inverse of arbitrary matrices (including singular and rectangular). We should note that we invoke ginv algorithm. In order to support and state our achievement we need to remind Gram-Schmidt orthonormalization (GSO) and the QR-factorization. 2.1. The Gram-Schmidt Procedure Let us remind a generalization of the Gram-Schmidt
Minimal blocking sets in PG(n,2) and covering groups by subgroups
Alireza Abdollahi,M. J. Ataei,A. Mohammadi Hassanabadi
Mathematics , 2007,
Abstract: In this paper we prove that a set of points $B$ of PG(n,2) is a minimal blocking set if and only if $=PG(d,2)$ with $d$ odd and $B$ is a set of $d+2$ points of $PG(d,2)$ no $d+1$ of them in the same hyperplane. As a corollary to the latter result we show that if $G$ is a finite 2-group and $n$ is a positive integer, then $G$ admits a $\mathfrak{C}_{n+1}$-cover if and only if $n$ is even and $G\cong (C_2)^{n}$, where by a $\mathfrak{C}_m$-cover for a group $H$ we mean a set $\mathcal{C}$ of size $m$ of maximal subgroups of $H$ whose set-theoretic union is the whole $H$ and no proper subset of $\mathcal{C}$ has the latter property and the intersection of the maximal subgroups is core-free. Also for all $n<10$ we find all pairs $(m,p)$ ($m>0$ an integer and $p$ a prime number) for which there is a blocking set $B$ of size $n$ in $PG(m,p)$ such that $=PG(m,p)$.
Prevalence of Transfusion Transmitted Virus Infection in Hemodialysis Patients and Injection Drug Users Compared to Healthy Blood Donors in Isfahan, Iran
Behrooz Ataei,Alireza Emami Naeini,Farzin Khorvash,Mohammad Reza Yazdani,Abbas-Ali Javadi
Gastroenterology Research and Practice , 2012, DOI: 10.1155/2012/671927
Abstract: Introduction. The pathogenicity and transmission routes of Transfusion Transmitted Virus (TTV) remain unclear. The aim of this study was to determine the prevalence of TTV in hemodialysis patients, injecting drug users (IDUs), and healthy blood donors, in Isfahan, Iran. Method. In a case-control study, a total of 108 subjects were put into three groups namely Group I, 36 hemodialysis patients; Group II, 36 IDUs; and Group III, 36 healthy blood donors as the control group. A 5 ml blood sample was collected from each subject in an EDTA-containing tube. Samples were tested for TTV DNA by means of real-time polymerase chain reaction (PCR). Results. The mean age was years. Seventy-one subjects (66%) were male. Of the108 cases, 30 (27.8%) were TTV positive and 78 (72.2%) were TTV negative. The prevalence of TTV in IDUs [21 (58%)] was significantly higher than in the other groups [group I: 6 (17 %) and group III: 3 (8%)] ( ). Conclusion. The prevalence of TTV in IDUs is significantly higher than in both hemodialysis patients and general population in Isfahan, Iran. It seems necessary to take serious measures to reduce the risk of TTV transmission to IDUs’ close contacts and health care providers. 1. Introduction Transfusion transmitted virus (TTV) was identified in 1997 in Japan in a patient with acute posttransfusion non-A-to-G hepatitis [1]. TTV is a nonenveloped, single-stranded virus with a wide genetic variety and a worldwide distribution. Its frequency varies in different parts of the world [2]. TTV is believed to be hepatotropic since its viral levels are observed to be higher in the liver than in the serum of infected patients. TTV has also been identified within hepatocytes, and was shown to replicate, by in situ hybridization and PCR; however, only minor morphologic changes have been seen in cells with positive hybridization signals [3]. TTV has been found in many body fluids including saliva, milk, tears and feces [4]. Parenteral [5], fecal-oral [6], mother to fetus and sexual [7] routes have been suggested for TTV transmission. It has been shown that TTV infection is associated with increased serum transaminases [8]. Relationship between TTV infection and posttransfusion hepatitis, acute hepatitis, and chronic liver disease with unknown etiology has also been proposed [8, 9]. However, this relationship has not yet been proved [10, 11]. The idea that TTV infection may increase the risk of hepatocellular carcinoma in patients with chronic HCV infection remains to be confirmed [12]. On the other hand, high prevalence of TTV infection in control groups
A survey on the effects of Azithromycin in the treatment of gingival overgrowth induced by Cyclosporin in renal transplant patients
Kadkhoda Z.,Ataei R.
Journal of Dental Medicine , 2004,
Abstract: Statement of Problem: Gingival overgrowth is a side effect commonly induced by Cyclosporin treatment. The effects of Azithromycin, a macrolidic antibiotic, has been focused on gingival enlargement treatment induced by cyclosporine in numerous articles. Purpose: The goal of the present study was to survey the effects of systemic Azithromycin in the treatment of gingival overgrowth induced by cyclosporine among renal transplant patients. Materials and Methods: In this clinical trial study, 18 renal transplant patients (6 females and 12 males) with gingival overgrowth were studied. Samples were randomly divided into two groups: case group were treated by systemic Azithromycin and controls were treated by systemic placebo. Periodontal parameters including bleeding on probing (BOP), clinical crown length (CL), periodontal pocket depth (PPD), gingival overgrowth (GOI) and stent-IDP (vertical distant between a stent or plate with teeth occlusal planes at least from three of the most anterior contact points to mesial papillae) before treatment, two and six weeks after treatment were measured. To analyze the data, Wilcoxon and Mann-Whitney tests were used. Results: Most of the measured indices, among case and control groups, were significantly improved, after two weeks (P<0.05). No statistically significant differences were found between two groups except for BOP index (P<0.05). In other words, more BOP improvement was observed in the case group after six weeks comparing to the control group. Conclusion: Considering the findings of this study, one can assume that the reported effects of Azithromycine on gingival overgrowth, induced by cyclosporine is somehow exaggerated and the effects attributed this medicine is probably inflammation reduction.
Comparative Evaluation of Human Bioclimatic of Isfahan city using the Terjung methods, TCI, PET, PMV
H. Ataei,S. Hasheminasab
Regional and Urban Studies and Research , 2012,
Abstract: Extended abstract1-IntroductionIt is very important to study and identify climatic limitations and threats and know attractions and potentialities of climatic specifications nationwide during different seasons in order to consider them in planning of national, provincial and urban levels. Thus, we can achieve a balance in climatic elements assessing bioclimate to create welfare for mankind. Thereby man can pave the ground to do livelihood activities. Therefore, the issue of welfare is very important and considerable for the continuity of human activities and his mental and physical evaluation. Since benefiting the available capacities in every region is a dynamic factor to develop region, Isfahan can play a very important role in job creation and economic and human development mainly because of its rich natural attractions. Therefore, the results of this research are very important in recognizing and introducing the changes of climatic elements and factors during different periods and the role of these factors in providing welfare in Isfahan.The aim of this research is to know human bioclimate and the influence of climatic parameters on the physiological structure of human in every month in Isfahan and to compare the results of various methods with each other. 2-MethodologyDescriptive, deductive and statistical methods have been used in this research. First, statistics were transferred to Excel Software and S-PLUS and then to Rayman Software fitting PET and PMV methods and finally the outputs were analyzed.To assess human bioclimate of Isfahan comparatively on the basis of PMV, PET, TCI and Terjung methods, climate parameters such as the mean average, the minimum and maximum temperature, the minimum and maximum relative humidity, average of sunshine hours, mean average of wind speed, average of vapor pressure, the amount of cloud in three synoptic stations including Isfahan, east of Isfahan and Kabootar-Abad during a eighteen- year statistical period (1992-2010) have been used. 3-DiscussionAccording to the assessment of different methods, it was determined that based on Terjung method the climate of three stations was pleasant in April and October and based on TCI factor, it was pleasant in April, September and October and partly pleasant in August. In east of Isfahan it was pleasant in May, September and October and partly pleasant in April. Kabootar-Abad had the best climatic condition in April, May and October and it was partly pleasant in November. Based on PET and PMV methods, all stations have pleasant climatic condition in May and September and pa
Minimal normal subgroups and semisimplity condition
M. J. Ataei
International Journal of Algebra , 2012,
Abstract:
An Actual Survey of Dimensionality Reduction  [PDF]
Alireza Sarveniazi
American Journal of Computational Mathematics (AJCM) , 2014, DOI: 10.4236/ajcm.2014.42006
Abstract:

Dimension reduction is defined as the processes of projecting high-dimensional data to a much lower-dimensional space. Dimension reduction methods variously applied in regression, classification, feature analysis and visualization. In this paper, we review in details the last and most new version of methods that extensively developed in the past decade.

The Introduction of Promising Mineral Zones Bidkhan Area Using Satellite Imagery  [PDF]
Alireza Ashofteh
Open Journal of Geology (OJG) , 2017, DOI: 10.4236/ojg.2017.79093
Abstract: On the basis of new findings and some evidences related to porphyry mineralization, the exploration region of Bidkhan is considered as a promising mineral region for discovery of porphyry sort deposits. The findings from various sections indicate that diverse topological events in a zonal and regional time span have resulted in physiochemical (thermodynamic) systems leading to expansive alterations (metamorphism) and mineralization in the central region of Bidkhan area. Alterations such as Propylitic, Silicating, Argillic, Phyllic and even Potassic concentrates at an area of about 10 km2 together with such structures as fissures have created the required and suitable condition for the formation of thermodynamic systems. Such systems are related to mineralization fluids mineralizer that accompanies the sort of activities that are clearly indicative of the existence of an active igneous source all forming a terrene at Bidkhan region which is very similar to mineralization porphyry systems.
Study Pressure Fields Affecting Cyclone Rainfall: Case Study of Iran  [PDF]
Iran Salehvand, Majid Montazeri, Amir Gandomkar, Mahdi Moemeni, Hoshmand Ataei
Atmospheric and Climate Sciences (ACS) , 2015, DOI: 10.4236/acs.2015.52010
Abstract: The aim of this study is the synoptic analysis of the atmospheric conditions concurrent with the heavy precipitations of Lorestan, Fars and Hormozgan provinces and determination of the temporal and spatial distribution of them. Requested atmospheric data for this research was taken from databases related to the National Organization of Atmosphere and Oceanology of United States. More maps of the site were taken. Then the earth surface, 500,700 and 850 Hecto Pascal maps, orbital and meridional winds, earth temperature of earth surface and top of the atmosphere were prepared in Grads software and some of maps were drawn in GIS software. The following results were obtained: On the earth surface map, the main controller role is with the Siberian high-pressure, the Azores’s dynamic high-pressure and integrated mode of the Sudan and the Mediterranean low-pressure systems. The main controller role in high levels is with the high altitude center of Azores in the back of the system, the high altitude center of Arabia in the front of the system and deep traffic of North Africa. Another important factor is the moisture mixture of Mediterranean Sea, Red Sea, Persian Gulf, Oman Sea and Indian Ocean. Air rise factor with enhancing meridional winds that causes subsidence of cold air, rising warm air and strengthening the polar front is one of the heavy rainfall conditions too. Eastern winds cause entering of moisture from the Indian Ocean and western winds cause strengthening of cyclones and heavy rainfall in the region.
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