نتایج جستجو برای: beam

تعداد نتایج: 113050  

In this article, M2 factor of a thin disk laser with unstable resonator in two regimes is calculated numerically. In the first case, thermal effects are ignored and the parameters of beam width, divergence angle, radius of wave front curvature and finally, M2 factor of laser beam are calculated by using generalized beam parameters. These calculations show that the beam quality of the laser is d...

First, this study obtained the fields of an Airy beam (AiB) with optical vortex (OV) for a Fourier transform (FT) system and a fractional Fourier transform (fractional FT) system; thereafter, their intensity and phase patterns were simulated numerically. The splitting on each line of the phase pattern indicates the position of an OV. The results show that the OV position will change when the po...

Journal: :journal of dentistry, tehran university of medical sciences 0
najmeh anbiaee associate professor of oral and maxillofacial radiology, oral and maxillofacial diseases research center, department of oral and maxillofacial radiology, school of dentistry, mashhad university of medical sciences, mashhad, iran. shadi saghafi associate professor, department of oral and maxillofacial pathology, oral and maxillofacial diseases research center, depart-school of dentistry, mashhad university of medical sciences, mashhad, iran. maryam mohammadzadeh rezaei department of oral and maxillofacial radiology, school of dentistry and dental research centre, mashhad university of medical sciences, mashhad, iran.

central granular cell odontogenic tumor) cgcot) of the jaw is an exceedingly rare benign odontogenic neoplasm with 35 reported cases in the literature. among these, very few studies have focused on the cone-beam ct features of cgcot. here, we report a case of an asymptomatic cgcot in a 16-year-old girl and focus on the cone-beam ct features. only 36 cases of this lesion, including this one, hav...

Journal: :Physical Review Special Topics - Accelerators and Beams 2012

Journal: :iranian journal of science and technology (sciences) 2015
qing-tian deng

functionally gradedpoisson’s ratio structures have been developed for critical protection. in thispaper, the static bending and buckling of fgpr nanoscale beam are studied basedon the nonlocal timoshenko beam model, in which both young’s modulus andpoisson’s ratio are assumed to vary continuously in the thickness direction. byutilizing total potential energy principle, equilibrium equations are...

A prismatic beam made of a behaviorally nonlinear material is analyzed under aharmonic load moving with a known velocity. The vibration equation of motion is derived usingHamilton principle and Euler-Lagrange Equation. The amplitude of vibration, circular frequency,bending moment, stress and deflection of the beam can be calculated by the presented solution.Considering the response of the beam,...

Abstract: It is assumed that a beam made of material has a physical nonlinear behavior. This beam is analyzed under the moving concentrated and distributed continuous loads. The vibration equations of motion are derived from the Hamilton's Principle and Euler–Lagrange Equation. In this study, the amplitude of vibration, circular frequency, bending moment, stress and deflection of the beam has b...

ژورنال: سنجش و ایمنی پرتو 2016

In order to achieve a thermal neutron beam for neutron radiography applications, a new neutron collimator has been designed, installed and characterized at Tehran Research Reactor (TRR). TRR is a 5 MW, open pool and light water coolant reactor with seven beam tubes. Neutron collimator that is an important part of neutron radiography system was installed in the six inch E beam tube. Collimator d...

H Guenfoud H Ziou, M Guenfoud M Himeur

Finite element formulations based generally on classical beam theories such as Euler-Bernoulli or Timoshenko. Sometimes, these two formulations could be problematic expressed in terms of restrictions of Euler-Bernoulli beam theory, in case of thicker beams due to non-consideration of transverse shear; phenomenon that is known as shear locking characterized the Timoshenko beam theory, in case of...

The static pull-in instability of beam-type micro-electromechanical systems is theoretically investigated. Two engineering cases including cantilever and double cantilever micro-beam are considered. Considering the mid-plane stretching as the source of the nonlinearity in the beam behavior, a nonlinear size-dependent Euler-Bernoulli beam model is used based on a modified couple stress theory, c...

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