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Aproximadamente 36 registro(s) hasta el momento: (journal)

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Recurso libre

Holographic photopolymer materials: nonlocal polymerization-driven diffusion under nonideal kinetic conditions
Kelly, John V. - O'Neill, Feidhlim T. - Sheridan, John T. - Neipp López, Cristian - Gallego Rico, Sergi - Ortuño Sánchez, Manuel

Formato:	info:eu-repo/semantics/article
Enlaces:	The kinetics of photosensitive polymer holographic recording materials are examined assuming a material that exhibits nonideal kinetic behavior. Previously, a linear relationship between monomer concentration and polymerization was assumed when deriving the nonlocal polymer-driven diffusion (NPDD) model. This is consistent…
Fecha:	2009-02-04
Recurso:	RUA Docencia

Recurso libre

An integrated project for teaching the post-buckling of a slender cantilever bar
Beléndez Vázquez, Tarsicio - Neipp López, Cristian - Beléndez Vázquez, Augusto

Formato:	info:eu-repo/semantics/article
Enlaces:	We describe an integrated project that includes theoretical, numerical and experimental studies designed to facilitate teaching the non-linear post-buckling of a cantilever column to undergraduate mechanical engineering students. We present the differential equation governing the behaviour of this mechanical system…
Fecha:	2009-03-10
Recurso:	RUA Docencia

Recurso libre

Stabilization of volume gratings recorded in polyvinyl alcohol-acrylamide photopolymers with diffraction efficiencies higher than 90%
Gallego Rico, Sergi - Neipp López, Cristian - Ortuño Sánchez, Manuel - Beléndez Vázquez, Augusto - Pascual Villalobos, Inmaculada

Formato:	info:eu-repo/semantics/article
Enlaces:	Obtaining holographic volume gratings with high diffraction efficiencies that can be used under white light has been a serious problem for the polyvinyl alcohol-acrylamide-based photopolymers developed by other researchers. In this paper we propose to eliminate the residual monomer in…
Fecha:	2009-02-03
Recurso:	RUA Docencia

Recurso libre

High-efficiency volume holograms recording on acrylamide and N,N'methylene-bis-acrylamide photopolymer with pulsed laser
Gallego Rico, Sergi - Ortuño Sánchez, Manuel - García Llopis, Celia - Neipp López, Cristian - Beléndez Vázquez, Augusto - Pascual Villalobos, Inmaculada

Formato:	info:eu-repo/semantics/article
Enlaces:	In order to achieve a better understanding of the mechanisms of hologram formation and higher diffraction efficiencies in volume gratings stored in acrylamide based photopolymers, a crosslinker (N,N'methylene-bis-acrylamide) has been incorporated in the photopolymer to record holograms by pulsed laser…
Fecha:	2009-02-02
Recurso:	RUA Docencia

Recurso libre

Angular responses of the first diffracted order in over-modulated volume diffraction gratings
Neipp López, Cristian - Álvarez López, Mariela Lázara - Gallego Rico, Sergi - Ortuño Sánchez, Manuel - Sheridan, John T. - Pascual Villalobos, Inmaculada - Beléndez Vázquez, Augusto

Formato:	info:eu-repo/semantics/article
Enlaces:	Kogelnik's coupled-wave (CW) theory has been used for decades to predict the diffraction efficiency of volume diffraction gratings. Although this theory has been applied with success to volume diffraction gratings recorded under a great variety of experimental conditions, its predictions…
Fecha:	2009-02-03
Recurso:	RUA Docencia

Recurso libre

Three approaches to calculating the velocity profile of a laminar incompressible fluid flow in a hollow tube
Neipp López, Cristian - Hernández Prados, Antonio - Beléndez Vázquez, Tarsicio - Rodes Roca, José Joaquín - Beléndez Vázquez, Augusto

Formato:	info:eu-repo/semantics/article
Enlaces:	We present three ways of treating the problem of fluid flow in a hollow cylinder. One method involves a differential equation, and the other two involve more physical insight. We discuss the relative advantages of each method., The following article…
Fecha:	2009-01-26
Recurso:	RUA Docencia

Recurso libre

Axial irradiance and entropy of holographic optical elements under illumination with quasi-monochromatic light
Carretero López, Luis - Beléndez Vázquez, Augusto - Fimia Gil, Antonio

Formato:	info:eu-repo/semantics/article
Enlaces:	The chromatic sensitivity of holographic optical elements for use in optical interconnect systems is quantified using an entropy merit function. The influence of broad-band illumination on axial irradiance and intensity is studied showing that the best imaging point obtained with…
Fecha:	2009-02-02
Recurso:	RUA Docencia

Recurso libre

An analysis of the classical Doppler effect
Neipp López, Cristian - Hernández Prados, Antonio - Rodes Roca, José Joaquín - Márquez Ruiz, Andrés - Beléndez Vázquez, Tarsicio - Beléndez Vázquez, Augusto

Formato:	info:eu-repo/semantics/article
Enlaces:	The Doppler effect is a phenomenon which relates the frequency of the harmonic waves generated by a moving source with the frequency measured by an observer moving with a different velocity from that of the source. The classical Doppler effect…
Fecha:	2009-01-30
Recurso:	RUA Docencia

Recurso libre

First-harmonic diffusion-based model applied to a polyvinyl-alcohol–acrylamide-based photopolymer
Neipp López, Cristian - Gallego Rico, Sergi - Ortuño Sánchez, Manuel - Márquez Ruiz, Andrés - Álvarez López, Mariela Lázara - Beléndez Vázquez, Augusto - Pascual Villalobos, Inmaculada

Formato:	info:eu-repo/semantics/article
Enlaces:	The photopolymerization diffusion models give accurate comprehension of the mechanism of hologram formation inside photopolymer materials. Although several models have been proposed, these models share the common assumption that there is an interplay between the processes of monomer polymerization and…
Fecha:	2009-01-22
Recurso:	RUA Docencia

Recurso libre

10.

Comparative study of bleaches applied to BB-640 plates
Neipp López, Cristian - Condeza, Shirley - Campos, Ana María - Pascual Villalobos, Inmaculada - Beléndez Vázquez, Augusto

Formato:	info:eu-repo/semantics/article
Enlaces:	The use of bleaching techniques is perhaps one of the most popular methods of creating phase holograms from holographic emulsions. In this paper we will study the influence of the different experimental conditions on the refractive index modulation created inside…
Fecha:	2009-01-30
Recurso:	RUA Docencia

Recurso libre

11.

Linearization of conservative nonlinear oscillators
Beléndez Vázquez, Augusto - Álvarez López, Mariela Lázara - Fernández Varó, Elena - Pascual Villalobos, Inmaculada

Formato:	info:eu-repo/semantics/article
Enlaces:	A linearization method of the nonlinear differential equation for conservative nonlinear oscillators is analyzed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force which allows us to obtain a frequency-amplitude relation which is valid…
Fecha:	2009-01-26
Recurso:	RUA Docencia

Recurso libre

12.

Imaging in white light with a thick-phase transmission holographic doublet
Beléndez Vázquez, Augusto - Pascual Villalobos, Inmaculada - Fimia Gil, Antonio

Formato:	info:eu-repo/semantics/article
Enlaces:	An afocal two-element holographic imaging system is presented. This system can be used to work in white light. The holographic optical elements (holographic lenses) are made as thick phase holograms on silver halide sensitized gelatin (SHSG) and they present a…
Fecha:	2009-01-30
Recurso:	RUA Docencia

Recurso libre

13.

A two step method for recording holographic optical elements with partially coherent light
Pascual Villalobos, Inmaculada - Beléndez Vázquez, Augusto - Fimia Gil, Antonio

Formato:	info:eu-repo/semantics/article
Enlaces:	We propose a two step method which enables us to obtain transmission Holographic Optical Elements of high diffraction efficiency as well as a good signal-to-noise relation. By means of a device using partially coherent light, a master Holographic Optical Element…
Fecha:	2009-01-30
Recurso:	RUA Docencia

Recurso libre

14.

Cables under concentrated loads: a laboratory project for an engineering mechanics course
Beléndez Vázquez, Tarsicio - Neipp López, Cristian - Beléndez Vázquez, Augusto

Formato:	info:eu-repo/semantics/article
Enlaces:	Cables are one of the common structures studied in a first-year engineering mechanics course (statics), since the flexible cable is one of the usual methods of supporting loads. For example, the suspension bridge has been used for many centuries and…
Fecha:	2009-01-27
Recurso:	RUA Docencia

Recurso libre

15.

Noise gratings in thick-phase holographic lenses
Beléndez Vázquez, Augusto - Fuentes Rosillo, Rosa - Fimia Gil, Antonio

Formato:	info:eu-repo/semantics/article
Enlaces:	An experimental analysis of noise gratings in holographic lenses is presented. Lenses are recorded as thick-phase holograms in bleached silver halide emulsion. The authors calculated noise grating efficiency by using the diffraction efficiency in points across a lens diameter. They…
Fecha:	2009-01-30
Recurso:	RUA Docencia

Recurso libre

16.

Transformation of wavefront aberrations of holographic lenses for a general position of the exit pupil
Beléndez Vázquez, Augusto - Carretero López, Luis - Fimia Gil, Antonio

Formato:	info:eu-repo/semantics/article
Enlaces:	Equations are derived for determining third-order wavefront aberrations in the plane of the exit pupil from the known aberration in the plane of a holographic lens. Using the transformation equations of wavefront aberration when the plane of the exit pupil…
Fecha:	2009-01-30
Recurso:	RUA Docencia

Recurso libre

17.

The contribution of fast neutrals to cathode erosion in glow discharges
Abril Sánchez, Isabel - Gras Martí, Albert - Vallés Abarca, José Antonio

Formato:	info:eu-repo/semantics/article
Enlaces:	We calculate the rate at which a target located at the cathode of a glow discharge is sputtered. The calculation involves two steps: (1) evaluation of the energy distribution functions of ions and neutrals impinging on the target; and (2)…
Fecha:	2013-01-07
Recurso:	RUA Docencia

Recurso libre

18.

Silver halide (sensitized) gelatin in Agfa-Gevaert plates: the optimized procedure
Fimia Gil, Antonio - Beléndez Vázquez, Augusto - Pascual Villalobos, Inmaculada

Formato:	info:eu-repo/semantics/article
Enlaces:	Silver halide sensitized gelatin (SHSG) is one of the most promising techniques for the fabrication of transmission holographic optical elements, achieving relatively high sensitivity of photographic material with the low scattering and high light stability of dichromated gelatin. In this…
Fecha:	2009-02-02
Recurso:	RUA Docencia

Recurso libre

19.

Model for analyzing the effects of processing on recording material in thick holograms
Beléndez Vázquez, Augusto - Pascual Villalobos, Inmaculada - Fimia Gil, Antonio

Formato:	info:eu-repo/semantics/article
Enlaces:	A new model to describe the influences of chemical processing on thick holograms is presented. The model is based on three hypotheses about the behaviour of holographic recording material during processing. Thickness variations and shear-type effects that are due to…
Fecha:	2009-01-22
Recurso:	RUA Docencia

Recurso libre

20.

Solution of the relativistic (an)harmonic oscillator using the harmonic balance method
Beléndez Vázquez, Augusto - Pascual Villalobos, Carolina - Méndez Alcaraz, David Israel - Neipp López, Cristian

Formato:	info:eu-repo/semantics/article
Enlaces:	The harmonic balance method is used to construct approximate frequency–amplitude relations and periodic solutions to the relativistic oscillator. By combining linearization of the governing equation with the harmonic balance method, we construct analytical approximations to the oscillation frequencies and periodic…
Fecha:	2009-01-29
Recurso:	RUA Docencia

Recurso libre

21.

Numerical and experimental analysis of a cantilever beam: a laboratory project to introduce geometric nonlinearity in mechanics of materials
Beléndez Vázquez, Tarsicio - Neipp López, Cristian - Beléndez Vázquez, Augusto

Formato:	info:eu-repo/semantics/article
Enlaces:	The classical problem of deflection of a cantilever beam of linear elastic material, under the action of an uniformly distributed load along its length (its own weight) and an external vertical concentrated load at the free end, is experimentally and…
Fecha:	2009-01-23
Recurso:	RUA Docencia

Recurso libre

22.

Harmonic balance approaches to the nonlinear oscillators in which the restoring force is inversely proportional to the dependent variable
Beléndez Vázquez, Augusto - Méndez Alcaraz, David Israel - Beléndez Vázquez, Tarsicio - Hernández Prados, Antonio - Álvarez López, Mariela Lázara

Formato:	info:eu-repo/semantics/article
Enlaces:	The second-order harmonic balance method is used to construct three approximate frequency-amplitude relations for a conservative nonlinear singular oscillator in which the restoring force is inversely proportional to the dependent variable. Two procedures are used to solve the nonlinear differential…
Fecha:	2009-01-26
Recurso:	RUA Docencia

Recurso libre

23.

Theoretical and experimental analysis of overmodulation effects in volume holograms recorded on BB-640 emulsions
Neipp López, Cristian - Pascual Villalobos, Inmaculada - Beléndez Vázquez, Augusto

Formato:	info:eu-repo/semantics/article
Enlaces:	Kogelnik's coupled-wave theory has provided a well-established basis for understanding how light propagates inside a volume hologram, giving an accurate approximation of the diffraction efficiency in this type of hologram. In this paper we elaborate on some aspects of the…
Fecha:	2009-01-30
Recurso:	RUA Docencia

Recurso libre

24.

Thick phase holographic gratings recorded on BB-640 and PFG-01 silver halide materials
Neipp López, Cristian - Márquez Ruiz, Andrés - Pascual Villalobos, Inmaculada - Beléndez Vázquez, Augusto

Formato:	info:eu-repo/semantics/article
Enlaces:	Photographic emulsions are still widely used to record holographic optical elements. In particular, if high diffraction efficiencies are needed, phase volume holograms are preferably recorded on these emulsions. Two particular techniques producing high-quality volume phase holograms are fixation-free rehalogenating bleaching…
Fecha:	2009-01-30
Recurso:	RUA Docencia

Recurso libre

25.

Large and small deflections of a cantilever beam
Beléndez Vázquez, Tarsicio - Neipp López, Cristian - Beléndez Vázquez, Augusto

Formato:	info:eu-repo/semantics/article
Enlaces:	The classical problem of the deflection of a cantilever beam of linear elastic material, under the action of an external vertical concentrated load at the free end, is analysed. We present the differential equation governing the behaviour of this physical…
Fecha:	2009-01-30
Recurso:	RUA Docencia

Recurso libre

26.

Mixed phase-amplitude holographic gratings recorded in bleached silver halide materials
Neipp López, Cristian - Pascual Villalobos, Carolina - Beléndez Vázquez, Augusto

Formato:	info:eu-repo/semantics/article
Enlaces:	The coupled wave theory of Kogelnik has given a well-established basis for the comprehension of how light propagates inside a volume hologram. This theory gives a good approximation for the diffraction efficiency of both volume phase holograms and volume absorption…
Fecha:	2009-01-30
Recurso:	RUA Docencia

Recurso libre

27.

Low spatial frequency characterization of holographic recording materials applied to correlation
Márquez Ruiz, Andrés - Neipp López, Cristian - Beléndez Vázquez, Augusto - Campos Coloma, Juan - Yzuel Giménez, María Josefa - Fimia Gil, Antonio

Formato:	info:eu-repo/semantics/article
Enlaces:	Accurate recording of computer-generated holograms (CGH) on a phase material is not a trivial task. The range of available phase materials is large, and their suitability depends on the fabrication technique chosen to produce the hologram. We are particularly interested…
Fecha:	2009-01-30
Recurso:	RUA Docencia

Recurso libre

28.

Asymptotic representations of the period for the nonlinear oscillator
Beléndez Vázquez, Augusto - Hernández Prados, Antonio - Beléndez Vázquez, Tarsicio - Neipp López, Cristian - Márquez Ruiz, Andrés

Formato:	info:eu-repo/semantics/article
Enlaces:	The asymptotic behaviours for small and large amplitudes, A, of the period for a nonlinear oscillator, where the square of the angular frequency depends quadratically on the velocity, are obtained. These asymptotic expressions are compared with the exact period, T(A),…
Fecha:	2007-10-27
Recurso:	RUA Docencia

Recurso libre

29.

The young open cluster Berkeley 55
Negueruela Díez, Ignacio - Marco Tobarra, Amparo

Formato:	info:eu-repo/semantics/article
Enlaces:	We present UBV photometry of the highly reddened and poorly studied open cluster Berkeley 55, revealing an important population of B-type stars and several evolved stars of high luminosity. Intermediate-resolution far-red spectra of several candidate members confirm the presence of…
Fecha:	2013-11-13
Recurso:	RUA Docencia

Recurso libre

30.

Application of homotopy perturbation method to the nonlinear pendulum
Beléndez Vázquez, Augusto - Hernández Prados, Antonio - Beléndez Vázquez, Tarsicio - Neipp López, Cristian - Márquez Ruiz, Andrés

Formato:	info:eu-repo/semantics/article
Enlaces:	The homotopy perturbation method is used to solve the nonlinear differential equation that governs the nonlinear oscillations of a simple pendulum, and an approximate expression for its period is obtained. Only one iteration leads to high accuracy of the solutions…
Fecha:	2007-10-27
Recurso:	RUA Docencia

Recurso libre

31.

Higher accurate approximate solutions for the simple pendulum in terms of elementary functions
Beléndez Vázquez, Augusto - Francés Monllor, Jorge - Ortuño Sánchez, Manuel - Gallego Rico, Sergi - Bernabeu Pastor, José Guillermo

Formato:	info:eu-repo/semantics/article
Enlaces:	A closed-form approximate expression for the solution of a simple pendulum in terms of elementary functions is obtained. To do this, the exact expression for the maximum tension of the string of the pendulum is first considered and a trial…
Fecha:	2010-05-03
Recurso:	RUA Docencia

Recurso libre

32.

A novel rational harmonic balance approach for periodic solutions of conservative nonlinear oscillators
Beléndez Vázquez, Augusto - Gimeno Nieves, Encarnación - Álvarez López, Mariela Lázara - Gallego Rico, Sergi - Ortuño Sánchez, Manuel - Méndez Alcaraz, David Israel

Formato:	info:eu-repo/semantics/article
Enlaces:	An analytical approximate procedure for a class of conservative single degree-of-freedom nonlinear oscillators with odd non-linearity is proposed. This technique is based on the generalized harmonic balance method in which analytical approximate solutions have rational forms. Unlike the classical harmonic…
Fecha:	2012-05-04
Recurso:	RUA Docencia

Recurso libre

33.

Development of a unified FDTD-FEM library for electromagnetic analysis with CPU and GPU computing
Francés Monllor, Jorge - Bleda Pérez, Sergio - Gallego Rico, Sergi - Neipp López, Cristian - Márquez Ruiz, Andrés - Pascual Villalobos, Inmaculada - Beléndez Vázquez, Augusto

Formato:	info:eu-repo/semantics/article
Enlaces:	The present paper describes an optimized C++ library for the study of electromagnetics. The implementation is based on the Finite-Difference Time-Domain method for transient analysis, and the Finite Element Method for electrostatics. Both methods share the same core and are…
Fecha:	2013-05-07
Recurso:	RUA Docencia

Recurso libre

34.

Temporal response and first order volume changes during grating formation in photopolymers
Kelly, John V. - Gleeson, Michael R. - Close, Ciara E. - O'Neill, Feidhlim T. - Sheridan, John T. - Gallego Rico, Sergi - Neipp López, Cristian

Formato:	info:eu-repo/semantics/article
Enlaces:	We examine the evolution of the refractive index modulation when recording gratings in an acrylamide based photopolymer. A nonlocal diffusion model is used to predict theoretically the grating evolution. The model has been developed to account for both nonlocal spatial…
Fecha:	2009-02-13
Recurso:	RUA Docencia

Recurso libre

35.

Simple model of bulk and surface excitation effects to inelastic scattering in low-energy electron beam irradiation of multi-walled carbon nanotubes
Kyriakou, Ioanna - Emfietzoglou, Dimitris - García Molina, Rafael - Abril Sánchez, Isabel - Kostarelos, Kostas

Formato:	info:eu-repo/semantics/article
Enlaces:	The effect of bulk and surface excitations to inelastic scattering in low-energy electron beam irradiation of multi-walled carbon nanotubes (MWNTs) is studied using the dielectric formalism. Calculations are based on a semiempirical dielectric response function for MWCNTs determined by means…
Fecha:	2012-11-29
Recurso:	RUA Docencia

Recurso libre

36.

Inelastic scattering of low-energy electrons in liquid water computed from optical-data models of the Bethe surface
Emfietzoglou, Dimitris - Kyriakou, Ioanna - Abril Sánchez, Isabel - García Molina, Rafael - Nikjoo, Hooshang

Formato:	info:eu-repo/semantics/article
Enlaces:	Purpose: We provide a short overview of optical-data models for the description of inelastic scattering of low-energy electrons (10–10,000 eV) in liquid water. The effect on the inelastic scattering cross section due to different optical data and extension algorithms is…
Fecha:	2012-07-04
Recurso:	RUA Docencia