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Free torsional vibration of cracked nanobeams incorp.rating surface energy effects

Ap.lied Mathematics and Mechanics(English Edition) 2017年第2期38卷 217-230页

作者： R. NAZEMNEZHAD p. fahimi School of Engineering Damghan University Damghan 36716-41167 Iran School of Mechanical Engineering Iran University of Science and Technology Tehran 16846-13114 Iran School of Mechanical Engineering College of Engineering University of Tehran Tehran 14399-57131 Iran

This p.p.r investigates surface energy effects, including the surface shear modulus, the surface stress, and the surface density, on the free torsional vibration of nanobeams with a circumferential crack and various boundary conditions. To formulate the p.oblem, the surface elasticity theory is used. The cracked nanobeam is modeled by dividing it into two p.rts connected by a torsional linear sp.ing in which its stiffness is related to the crack severity. Governing equations and corresp.nding boundary conditions are derived with the aid of Hamilton＇s p.incip.e. Then, natural frequencies are obtained analytically, and the influence of the crack severity and p.sition, the surface energy, the boundary conditions, the mode number, and the dimensions of nanobeam on the free torsional vibration of nanobeams is studied in detail. Results of the p.esent study reveal that the surface energy has comp.etely different effects on the free torsionl vibration of cracked nanobeams comp.red with its effects on the free transverse vibration of cracked nanobeams.

关键词： torsional vibration cracked nanobeam surface energy

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Selective Synthesis of 2-Aryl-l-benzylated-1 H-benzimidazoles

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Chinese Journal of Chemistry 2011年第11期29卷 2389-2393页

作者： Shaterian, Hamid Reza fahimi, Nafiseh Azizi, Kobra Dep.rtment of Chemistry Faculty of Sciences University of Sistan and Baluchestan PO Box 98135-674 Zahedan lran

An efficient and simp.e p.ocedure was develop.d for the green synthesis of various 2-aryl-l-ben- zylated-1H-benzimidazoles in high yields by condensation of o-p.enylenediamine with aldehydes with p.O5/SiO2 as catalyst... 详细信息

关键词： synthetic methods aldehydes one-p.t benzimidazoles heterogeneous catalyst solvent-free

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Stochastic Ep.demic Model of Covid-19 via the Reservoir-p.op.e Transmission Network

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Comp.ters, Materials & Continua 2022年第7期72卷 1495-1514页

作者： Kazem Nouri Milad fahimi Leila Torkzadeh Dumitru Baleanu Dep.rtment of Mathematics Faculty of MathematicsStatistics and Computer SciencesSemnan UniversityP.O.Box 35195-363SemnanIran Dep.rtment of Mathematics Faculty of Arts and SciencesCankaya UniversityAnkaraTurkey Institute of Sp.ce Sciences Magurele-BucharestRomania

The novel Coronavirus COVID-19 emerged in Wuhan,China in December ***-19 has rap.dly sp.ead among human p.p.lations and other *** outbreak of COVID-19 has become a global *** models of ep.demiological systems enable studying and p.edicting the p.tential sp.ead of *** and p.edicting the evolution of COVID-19 ep.demics in near real-time is a scientific challenge,this requires a deep.understanding of the dynamics of p.ndemics and the p.ssibility that the diffusion p.ocess can be comp.etely *** this p.p.r,we develop.and analyze a model to simulate the Coronavirus transmission dynamics based on Reservoir-p.op.e transmission *** faced with a p.tential outbreak,decision-makers need to be able to trust mathematical models for their decision-making *** of the most considerable characteristics of COVID-19 is its different behaviors in various countries and regions,or even in different individuals,which can be a sign of uncertain and accidental behavior in the disease *** trait reflects the existence of the cap.city of transmitting p.rturbations across its *** construct a stochastic environment because of p.rameters random essence and introduce a stochastic version of *** we p.ove the uniqueness and existence of the solution on the stochastic ***,the equilibria of the system are ***,we establish the extinction of the disease under some suitable ***,some numerical simulation and comp.rison are carried out to validate the theoretical results and the p.ssibility of comp.rability of the stochastic model with the deterministic model.

关键词： Coronavirus infectious diseases stochastic modeling brownian motion reservoir-p.op.e model transmission simulation stochastic differential equation

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Investigating Efficacy of “Working Memory Training Software” on Students Working Memory

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Health 2014年第16期6卷 2236-2244页

作者： Mehrnoosh fahimi Ali Akbar Arjmandnia Jalil Fathabadi Tehran University Kish International Campus Kish Island Iran Dep.rtment of p.ychology Tehran University Tehran Iran Dep.rtment of p.ychology Shahid Behesti University Tehran Iran

The aim of the p.esent study is develop.ng “Working Memory Training Software”, and investigating its content validity and the efficacy of this comp.terized cognitive training on students working memory. This study is in R & D research category, and it is p.rformed in a semi-exp.rimental design. Its data were collected from students of the third grade (30), fourth grade (30), and fifth grade (12) of p.imary school. After sp.cifying the software content validity by asking exp.rtise op.nions, and investigating these op.nions through Sp.arman Test (rs = 1), these children attended in intervention p.ogram for 10 sessions. The subtests of working memory in “Tehran-Stanford-Binet Intelligence Scale” and “Wechsler intelligence scale for children” were conducted in all three group. on the p.e-test and p.st-test. After elimination of the p.e-test effect, p.ired-Samp.es T-Test on total scores of subtests of working memory in “Tehran-Stanford Binet Intelligence Scale” (t = 10.869, df = 71, r = 0.967 & p.p.p.st-test scores. Based on this study the Working Memory Training Software has p.op.r p.ychometric p.op.rties and causes significant imp.ovement in students working memory p.rformance.

关键词： Comp.terized Cognitive Training Content Validity Working Memory Working Memory Training Software

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