Search results for "beams"

Some comments on the experimental behavior of FRC beams in flexure

2008

In the present paper the experimental results, recently obtained by the authors, regarding the monotonic and the cyclic flexural response of normal and high-strength concrete beams reinforced with steel bars and discontinuous fibers, are shown. From the experimental results, all referred to low values of shear-to-depth ratios, it emerges clearly that the shear failure is brittle especially under cyclic actions highlighting the role of the fibers in the flexural behavior of the beams. The cyclic action produces a significant decay in the stiffness and in the strength capacity of the beams, and the addition of fibers reduces these negative effects. Form theoretical point of view good agreemen…

Simplified Model of PC Concrete Beams with Corroded Strands in Highway Viaduct: Case Study and Analytical Modeling

2021

AbstractIn this paper, several cases of failure of prestressed reinforced concrete (PC) beams of a viaduct in Italy due to cable corrosion are presented. Therefore, a simplified model to determine ...

Optical Fibers Enter a New Space-Time Era

2016

We show experimentally a new type of parametric instability associated with the original phenomenon of beam self-cleaning in multimode fibers. Our experimental results are in good agreement with numerical solutions of the Gross-Pitaevskii equation.

Generation of Pair Coherent States in Two-dimensional Trapped Ion

2001

We consider a two-dimensional (2D) trapped ion model in which two laser beams drive the corresponding vibrational motions and are carrier resonant with the two-level of the ion. Due to the coherent superposition of two sub-Rabi oscillations involved in the bimodal vibrations, the Rabi frequency degeneration and offset may occur in this model. This provides the possibility of generating the pair coherent state in the 2D trapped ion.

Cylindrical Cuvette Light Refraction Measurements Technology to Analyse Biomedical Liquids

2015

Compact device of high sensitivity for measurement of the refractive indices for both stationary and flowing liquids has been developed. This device can be used to analyse a variety of biomedical liquids: urine, serum protein. The refractive index (RI) is determined by measuring the deviation of a laser beam passing through a cylindrical cuvette containing the test liquid. In order to significantly improve the resolution and stability of RI measurements, the repeated reflections and refractions of the light beam travelling through the cylindrical cuvette are employed.

Hamiltonian tools for the analysis of optical polarization control

2011

Import JabRef; International audience; The study of the polarization dynamics of two counterpropagating beams in optical fibers has recently been the subject of a growing renewed interest, from both the theoretical and experimental points of view. This system exhibits a phenomenon of polarization attraction, which can be used to achieve a complete polarization of an initially unpolarized signal beam, almost without any loss of energy. Along the same way, an arbitrary polarization state of the signal beam can be controlled and converted into any other desired state of polarization, by adjusting the polarization state of the counterpropagating pump beam. These properties have been demonstrate…

Design, construction and cooling system performance of a prototype cryogenic stopping cell for the Super-FRS at FAIR

2015

A cryogenic stopping cell for stopping energetic radioactive ions and extracting them as a low energy beam was developed. This first ever cryogenically operated stopping cell serves as prototype device for the Low-Energy Branch of the Super-FRS at FAIR. The cell has a stopping volume that is 1 m long and 25 cm in diameter. Ions are guided by a DC field along the length of the stopping cell and by a combined RF and DC fields provided by an RE carpet at the exit-hole side. The ultra-high purity of the stopping gas required for optimum ion survival is reached by cryogenic operation. The design considerations and construction of the cryogenic stopping cell, as well as some performance character…

Multiplexing THz Vortex Beams With a Single Diffractive 3-D Printed Lens

2019

[EN] We present a novel method for experimentally generating multiplexed THz vortex beams by using a single three-dimensional printed element that combines a set of radially distributed spiral phase plates, and a binary focusing Fresnel lens. With this element, we have experimentally demonstrated that THz multiplexing can be tailored to fit within a small space on an optical bench. Results are presented beside numerical simulations, demonstrating the robust nature of the experimental method.

Diffraction-free beams in thin films

2009

The propagation and transmission of Bessel beams through nano-layered structures has been discussed recently. Within this framework we recognize the formation of unguided diffraction-free waves with the spot size approaching and occasionally surpassing the limit of a wavelength when a Bessel beam of any order n is launched onto a thin material slab with grazing incidence. On the basis of the plane-wave representation of cylindrical waves, a simple model is introduced providing an exact description of the transverse pattern of this type of diffraction-suppressed localized wave. Potential applications in surface science are put forward for consideration. Ministerio de Ciencia e Innovación (MI…

On the moving loads problem in discontinuous homogeneous beams and layered beams with interlayer slip

This manuscript contains the main part of my research performed in this last triennium at the Department of Civil, Environmental, Aerospace and Materials Engineering, University of Palermo, and at the Department of Basic Sciences in Engineering Sciences (Unit of Applied Mechanics), University of Innsbruck, Austria. The research adheres to a common procedure of solving a scientistic problem. That is, introduction to the problem, selection of the mathematical and physical tools to model the problem, proposed solution, and numerical validation. The thesis proposes a novel modal superposition approach to the moving loads problem on discontinuous homogeneous beam and layered beam with interlayer…