oalib

OALib Journal期刊

ISSN: 2333-9721

费用:99美元

投稿

时间不限

2017 ( 362 )

2016 ( 737 )

2015 ( 10822 )

2014 ( 13758 )

自定义范围…

匹配条件: “Asgari S” ,找到相关结果约324353条。
列表显示的所有文章,均可免费获取
第1页/共324353条
每页显示
Sensitivity Analysis of the Influence of Structural Parameters on Dynamic Behaviour of Highly Redundant Cable-Stayed Bridges
B. Asgari,S. A. Osman,A. Adnan
Advances in Civil Engineering , 2013, DOI: 10.1155/2013/426932
Abstract: The model tuning through sensitivity analysis is a prominent procedure to assess the structural behavior and dynamic characteristics of cable-stayed bridges. Most of the previous sensitivity-based model tuning methods are automatic iterative processes; however, the results of recent studies show that the most reasonable results are achievable by applying the manual methods to update the analytical model of cable-stayed bridges. This paper presents a model updating algorithm for highly redundant cable-stayed bridges that can be used as an iterative manual procedure. The updating parameters are selected through the sensitivity analysis which helps to better understand the structural behavior of the bridge. The finite element model of Tatara Bridge is considered for the numerical studies. The results of the simulations indicate the efficiency and applicability of the presented manual tuning method for updating the finite element model of cable-stayed bridges. The new aspects regarding effective material and structural parameters and model tuning procedure presented in this paper will be useful for analyzing and model updating of cable-stayed bridges. 1. Introduction In the past decade the construction of cable-stayed bridges has increased and their span lengths are growing due to improvements in design and analysis technologies. However, the complex structural characteristics of long-span cable-stayed bridges cause difficulties in understanding their dynamic behavior and make them vulnerable to dynamic loadings from phenomena such as wind or earthquakes. In recent years, many experimental and analytical investigations have studied effective factors on the dynamic behavior of cable-stayed bridges, such as natural periods, mode shapes, and damping properties [1–5]. The sensitivity analysis is a promising way to provide a tuned analytical model and assess the actual dynamic characteristics of superstructures such as cable-stayed bridges. Sensitivity analysis is a technique to determine the influence of different properties, such as boundary conditions, damping properties, material constants, and geometrical parameters, on the structural responses. A number of sensitivity methods for model updating purposes have been proposed for different structures [6–12]; there have been successful applications of sensitivity-based updating technology for bridges in recent years. Cantieni [13] and Pavic et al. [14] were among the first to investigate the model updating of bridges using the sensitivity method. Mackie and Stojadinovi? [15] conducted a sensitivity study to
The Relationship Between Blood Group and Type 2 Diabetes
Emam, S J,Asgari, M.,Hosseini, S A,Shahbazian, H.
Medical Laboratory Journal , 2012, DOI: http://www.goums.ac.ir/mljgoums/index.php?&slct_pg_id=10&sid=1&slc_lang=en
Abstract: Background and objectives: Diabetes is a chronic and progressivedisease resulting in disability and premature death. The Etiology ofdiabetes mellitus is complex, but factors such as genetic,immunological and environmental are involved .The aim of this studywas to investigate the association between diabetes and blood type.Material and Methods: In this cross - sectional study, the bloodgroup of 500 patients with diabetes type 2 was determined andcompared with the distribution of blood groups in 11,461 healthypeople in Ahwaz. Statistical analysis was performed by independent Ttest, using SPSS Software (version 17)Results: the Patients’ age is between 35 and 80 years. Their Bloodgroups are A (106; 20.3 %) B (144; 27.5%) AB (97; 18.5%) andO(176; 32.7%). One hundred seventy-nine (34.2%) cases are Rh+ andthe rest (344; 65.8 %) Rh- .Conclusion: Regarding to the distribution of blood group AB andRh- ,which respectively are 7.3% and 8.4%, the chance of developingdiabetes in theses people is higher than that in other people(P<0.05). Hence, they should follow a healthy lifestyle from earlyyears of life to reduce the risk of diabetes.Key words: Diabetes type 2, Blood group, Risk factors
A molecular survey of Chlamydia trachomatis infection in married women: a cross sectional study on 991 women
Chamani-Tabriz L,Tehrani MJ,Zeraati H,Asgari S
Tehran University Medical Journal , 2008,
Abstract: "n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 st1":*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: Chlamydia trachomatis is a common and curable STI that may be symptomatic or asymptomatic. The few studies on C. trachomatis among Iranian women have had, for the most part, small sample sizes and are therefore unsuitable for epidemiological deductions. The aim of this study was to estimate the prevalence of urogenital C. trachomatis infections by PCR on urine samples of married women in their fertile years in order to determine the need for a C. trachomatis screening program for asymptomatic women in Iran."n"n Methods: This descriptive-analytical and cross-sectional study was performed on 991 married women. The research material consisted of questionnaires and urine samples, which were transported daily to Avesina Research Institute, Tehran, Iran, to extract their DNA and prepare them for PCR tests. The gathered data were analyzed by SPSS, version 13, and evaluated statistically by t-test, chi-square test, Fisher's exact test and logistic regression, considering p<0.05 as significant."n"n Results: Of all the subjects, 127 (12.8%) were positive by PCR for C. trachomatis. The mean age of the participants was 28.88± 6.19 years. Infection was more prevalent among those with lower levels of education, who were employed and not pregnant. This infection was more prevalent among those who were using contraception, especially condoms. Reproductive history revealed that infection was more prevalent among participants with a history of vaginal discharge, pelvic pain, infertility and low birth-weight infants, and less prevalent among those with a history of abortion, preterm delivery and ectopic pregnancy. However, these patterns were not statistically significant."n"n Conclusion: In populations with C. trachomatis prevalences higher than 4%, screening programs are recommended. Thus, Chlamydia s
Detection of Chlamydia trachomatis and Mycoplasma genitalium in semen samples of infertile men using multiplex PCR
Sadrpour P,Bahador A,Asgari S,Bagheri R
Tehran University Medical Journal , 2013,
Abstract: Background: Chlamydia trachomatis is the most common bacterial sexually transmitted infection in the world, but the effect of this infection on male fertility is still controversial. Despite reports of interaction between Mycoplasma genitalium and sperm, this pathogen in semen samples of infertile men is less studied. We studied, the prevalence of Chlamydia trachomatis and Mycoplasma genitalium infection in infertile men.Methods: Among attending Avicenna Infertility Center, 120 men who had abnormal semen analysis tests were selected and the samples were taken. After detailed analysis of semen quality, DNA was extracted from each sample by chelex. Samples were evaluated for these two pathogens by multiplex PCR. Results were statistically analyzed.Results: Chlamydia trachomatis and Mycoplasma genitalium was detected in 23/3% and 12/5% of the samples, respectively. Although, Mycoplasma genitalium infection rises by increasing (P=0.640) and decreasing in age of first sexually activity (P=0.203), and also positive cases of Chlamydia trachomatis infection showed increase regarding age increase (P=0.619) and age decrease in first sexually activity (P=0.511), but these differences were not statistically significant. Conclusion: All in all, regarding to the increased prevalence of Chlamydia trachomatis infection compared with the only similar study in Iran and high prevalence of Mycoplasma genitalium infection in infertile men, this assessment was done. A multiplex PCR protocol rapidly and simultaneously identify these organisms in comparison with uniplex from clinical samples. Based on our results screening for Chlamydia trachomatis and Mycoplasma genitalium infection among infertile men seems to be valuable.
Housewives’ Obesity Determinant Factors in Iran; National Survey - Stepwise Approach to Surveillance
S Navadeh,L Sajadi,A Mirzazadeh,F Asgari
Iranian Journal of Public Health , 2011,
Abstract: "nBackground: Women suffer more from obesity than men in Iran do. In this study, we compared obesity risk and its con-tributors regarding the job categories as housewives (HWs) or employees to deeply explore the risk of obesity in house-wives in Iran."nMethods: Based on WHO stepwise approach, in 2005, 33472 women aged 15 to 65 years old (excluding all men) were ex-amined for the major risk factors for non-communicable diseases. Obesity was determined by Body Mass Index>30kgm-2 in adults (>20 years) and by girl BMI percentiles according to WHO 2007 Growth Reference 5-19 years in adolescents. We modeled obesity by logistic regression and entered all the known/potential predictors, including job categories."nResults: The participation rate was more than 99%. The weighted prevalence of overweight and obesity in HWs were 34.5% and 24.5% respectively. Employed women were about 4% and 10% less overweight and obese than the HWs, respec-tively (P< 0.01). HWs vs. employed women had the adjusted OR 1.39 (CI95%, 1.18-1.63) for obesity. Older women, with higher educational level and socioeconomic status, lower physical activities and those living in urban areas were at risk of obesity. In comparison to HWs, working as an Official Clerk (OR=0.66) associated with a decrease in odds of obe-sity significantly, while others did not."nConclusion: Being as HW is an independent significant factor for obesity in women. Preventive health care programs to re-duce risk of obesity in women should be applied, considering their occupation for achieving more effectiveness.
Survey the Amount of Heavy Metals in Cultural Vegetables in Suburbs of Shahroud
S Nazemi,A.R Asgari,M Raei
Iranian Journal of Health and Environment , 2010,
Abstract: "n "nBackgrounds and Objectives : Vegetables are one of the most important components of daily food. Contamination of vegetables with heavy metals might ends to accumulate in the body, there for in this study the level of lead, chromium, cadmium, arsenic and zinc in cultural vegetables of shahroud suburb were measured in 1387."nMaterials and Methods : In this cross-sectional descriptive study, 150 vegetable samples through 3 months, 50 for each month, were randomly harvested. Atomic absorption instrument was used to determine the amount of mentioned heavy metals after sample preparation, SPSS whit 0.05 was used for statistically data analyzing."nResults : For vegetables the average value of Pb, Cr and Cd in different vegetables were different from each other and P value was less than<0.001. There are no significant amounts of Arsenic concentration. The value of these metals with 95% acceptable level was in the range of satisfaction. Arsenic didn't have that much of error of its contamination"nConclusion : Except Zn and As other metals like Cr, Cd and Pb were above the standard zone by FAO&WHO. The wastewaters of urban and industrial facilities are the main reason for this problem.The best suggestion is using pure water for this purpose.
Analytic theory of pair distribution functions in symmetric electron-electron and electron-hole bilayers
S. H. Abedinpour,R. Asgari,M. Polini,M. P. Tosi
Physics , 2007, DOI: 10.1016/j.ssc.2007.07.015
Abstract: We present a self-consistent analytic theory of the intra-layer and inter-layer pair correlation functions in electron-electron and electron-hole fluid bilayer systems. Our approach involves the solution of a zero-energy scattering Schroedinger equation with an effective potential which includes a Bose-like term from Jastrow-Feenberg correlations and a Fermi term from kinetic energy and exchange, tailored to yield the Hartree-Fock limit at high carrier density. The theory is also shown to satisfy the plasmon sum rule and the charge neutrality condition. We obtain good agreement with the available Quantum Diffusion Monte Carlo (DMC) data in symmetric bilayers over a wide range of carrier density and layer spacing, and stress the role of three-body correlation terms in yielding fully quantitative agreement at strong coupling. Signals of impending transitions to density-modulated states at strong coupling and low layer spacing appear in the calculated pair correlations through inter-layer in-phase oscillations for electron-hole bilayers and out-of-phase oscillations for electron-electron bilayers, in agreement with the DMC findings.
Ruderman-Kittel-Kasuya-Yosida interaction in biased bilayer graphene
F. Parhizgar,M. Sherafati,Reza Asgari,S. Satpathy
Physics , 2013, DOI: 10.1103/PhysRevB.87.165429
Abstract: We study the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between two contact magnetic impurities placed on bilayer graphene (BLG). We compute the interaction mediated by the carriers of the pristine and biased BLG as well as the conduction electrons of the doped system. The results are obtained from the linear-response expression for the susceptibility written in terms of the integral over lattice Green's functions. For the unbiased system, we obtain some analytical expressions in terms of the Meijer G-functions, which consist of the product of two oscillatory terms, one coming from the interference between the two Dirac points and the second coming from the Fermi momentum. In particular, for the undoped BLG, the system exhibits the RKKY interaction commensurate with its bipartite nature as expected from the particle-hole symmetry of the system. Furthermore, we explore a beating pattern of oscillations of the RKKY interaction in a highly doped BLG system within the four-band continuum model. Besides, we discuss the discrepancy between the short-range RKKY interaction calculated from the two-band model and that obtained from the four-band continuum model. The final results for the applied gate voltage are obtained numerically and are fitted with the functional forms based on the results for the unbiased case. In this case, we show that the long-range behavior is scaled with a momentum that depends on Fermi energy and gate voltage, allowing the possibility of tuning of the RKKY interaction by gate voltage.
Anisotropic RKKY interaction in spin polarized graphene
F. Parhizgar,Reza Asgari,S. H. Abedinpour,M. Zareyan
Physics , 2012, DOI: 10.1103/PhysRevB.87.125402
Abstract: We study the Ruderman-Kittle-Kasuya-Yosida (RKKY) interaction in the presence of spin polarized two dimensional Dirac fermions. We show that a spin polarization along the z-axis mediates an anisotropic interaction which corresponds to a XXZ model interaction between two magnetic moments. For undoped graphene, while the $x$ part of interaction keeps its constant ferromagnetic sign, its $z$ part oscillates with the distance of magnetic impurities, $R$. A finite doping causes that both parts of the interaction oscillate with $R$. We explore a beating pattern of oscillations of the RKKY interaction along armchair and zigzag lattice directions, which occurs for some certain values of the chemical potential. The two characteristic periods of the beating are determined by inverse of the difference and the sum of the chemical potential and the spin polarization.
Many-body effects in low dimensional electron liquids
R. Asgari
Iranian Journal of Physics Research , 2008,
Abstract: This review article is about the role of electron-electron interactions in low dimensional systems and its transport properties in nano-structures. It begins with a review of the pair-distribution function theory of electron liquid systems taking into account the electron-electron interactions. We extend the theory for highly correlated system such two- and one-dimensional electron liquids. We then review the microscopic theory of the local-field factors and calculate the quasiparticle properties in two-dimension electron liquid and compare our results with those measured by recent experiments. The physics of two-dimension bilayer structures are revised and are immediately applied to the study of charged Coulomb drag effects in a bilayer electron-electron system and results are compared with experimental data. As a final application, the Luttinger theory is discussed and we compare our recent calculations with those obtained from quantum Monte Carlo simulation for one dimensional electron liquid.
第1页/共324353条
每页显示


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