David Méndez

• University of Alicante

We report the findings of a diachronic study of 100 research paper abstracts published in four different periods (from 1943 to 2018) in Monthly Notices of the Royal Astronomical Society , one of the most prestigious astrophysics journals written in English. Our main results show that research paper abstracts have evolved over time in the sense that...

In this study we compare the titles of scientific letters and those of research papers published in the field of astrophysics in order to identify the possible differences and/or similarities between both genres in terms of several linguistic and extra-linguistic variables (length, lexical density, number of prepositions, number of compound groups,...

Introduction. We report an investigation on collaboration practices in research papers published in the most prestigious English-medium astrophysics journals. Method. We propose an evaluation method based on three numerical indicators to study and compare, in absolute terms, three different types of collaboration (international, national and local)...

En este póster presentamos las líneas de trabajo de la red docente RAFIA: evaluación formativa en la resolución de problemas y prácticas de laboratorio aplicados a situaciones propias de la ingeniería o de la arquitectura, la elaboración de materiales para el autoaprendizaje de la física y la utilización de blogs para las asignaturas de física para...

We present strategies to discover and characterise optical/infrared unknown counterparts to X-ray binary systems.

We analyze Astrophysics titles published in Scientific American Magazine in the period 1990-2014 and compare them with Astrophysics titles of specialized journals. Our main results show that titles published in Scientific American are short, clear, direct and with low lexical density and little terminology. They mainly consist in simple and nominal...

La preparación previa del alumnado que cursa la asignatura de Fundamentos Físicos en primer curso de grado implantado en la Escuela Politécnica Superior de la Universidad de Alicante, es muy heterogénea. Además, se da la circunstancia que en los últimos cursos alrededor de un 50% del alumnado no ha cursado nunca una asignatura de física anteriormen...

In the framework of an ongoing programme, we have developed strategies to discover and characterize optical/infrared unknown counterparts to X-ray binary systems using the standard tools of the Virtual Observatory. First, we have selected some potential candidates from different X-ray catalogues. Then we have used the Virtual Observatory tools to s...

Cuando finalice el curso 2013-14 se producirá la salida de la primera promoción de graduados en la Escuela Politécnica Superior (EPS). Teniendo en cuenta que antes de que transcurran seis años se debe renovar la acreditación de los títulos oficiales de Grado, consideramos adecuado efectuar un análisis crítico del proceso de enseñanza-aprendizaje. E...

He’s homotopy perturbation method is adapted to calculate higher-order approximate periodic solutions of conservative nonlinear oscillators for which the elastic force term is an odd nonlinear function. The method is modified by truncating the infinite series corresponding to the first-order approximate solution before introducing this solution in the...

In this study we analyse a corpus of 300 randomly selected research paper titles written in English and published between 1998 and 2012 in the most prestigious journals in the field of Astrophysics, an under-researched discipline from a linguistic standpoint. We specifically address issues related to the evolution of titles, their length, their lex...

En el presente proyecto hemos desarrollado un sistema de evaluación integral para las asignaturas de Física y Óptica del Grado en Ingeniería en Sonido e Imagen de la Universidad de Alicante. Nuestro sistema de evaluación contempla tres etapas fundamentales: una evaluación inicial para detectar las ideas previas del alumnado favoreciendo su otivació...

Póster presentado en las III Jornadas de Innovación Tecnológico Educativa, Universidad de Alicante, 2 de febrero de 2006. Este trabajo ha sido subvencionado por el Vicerrectorado de Convergencia Europea y Calidad (convocatoria 2003-04) y por el Vicerrectorado de Tecnología e Innovación Educativa (convocatoria 2004-05) de la Universidad de Alicante.

An accurate closed-form solution for the quintic Duffing equation is obtained using a cubication method. In this method the restoring force is expanded in Chebyshev polynomials and the original nonlinear differential equation is approximated by a cubic Duffing equation in which the coefficients for the linear and cubic terms depend on the initial a...

An analytical approximate technique for conservative nonlinear oscillators is proposed. This method is a modification of the generalized harmonic balance method in which analytical approximate solutions have a rational form. This approach gives us not only a truly periodic solution but also the frequency of motion as a function of the amplitude of...

Photopolymers are useful for different applications such as in the development of holographic memories or holographic optical elements. Photopolymers have an undesirable feature, the toxicity of their components and their low environmental compatibility, particularly if we analyse the life cycle of the devices made with these materials and their in...

Next academic year 2010/2011 next degrees will begin in the University of Alicante. In particular, in the Polytechnic High School will start 7 new degrees adequate to the “Real Decreto 1393/2007”. Recently Spanish government has described the new legislation to organize the new university degrees according the European Higher Education Area. The re...

A generalized harmonic balance method is used to calculate the periodic solutions of a nonlinear oscillator with discontinuities for which the elastic force term is proportional to . This method is a modification of the generalized harmonic balance method in which analytical approximate solutions have rational form. This approach gives us not only...

Photopolymers are appealing materials for the fabrication of diffractive optical elements (DOEs). We evaluate the possibilities of polyvinyl-alcohol/acrylamide-based photopolymers to store diffractive elements with low spatial frequencies. We record gratings with different spatial frequencies in the material and analyze the material behavior measur...

The nonlinear oscillations of a Duffing-harmonic oscillator are investigated by an approximated method based on the ‘cubication’ of the initial nonlinear differential equation. In this cubication method the restoring force is expanded in Chebyshev polynomials and the original nonlinear differential equation is approximated by a Duffing equation in...

Polyvinyl/acrylamide (PVA/AA) photopolymers are often used as holographic recording materials. Depending on each particular application, different spatial frequencies can be recorded. The only limitation appears when high spatial frequencies are stored (over 2500 lines/mm the diffraction efficiencies achieved are very low). This cut-off spatial fre...

The analytical approximate technique developed by Wu et al. for conservative oscillators with odd nonlinearity is used to construct approximate frequency-amplitude relations and periodic solutions to the relativistic oscillator. By combining Newton's method with the method of harmonic balance, analytical approximations to the oscillation period and...

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 balance techniques, in this new procedure t...

A modified He's homotopy perturbation method is used to calculate the periodic solutions of a nonlinear pendulum. The method has been modified by truncating the infinite series corresponding to the first-order approximate solution and substituting a finite number of terms in the second-order linear differential equation. As can be seen, the modifie...

An analytical approximate technique for conservative nonlinear oscillators is proposed. This method is a modification of the rational harmonic balance method in which analytical approximate solutions have rational form. This approach gives us the frequency of the motion as a function of the amplitude of oscillation. We find that this method works v...

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 equation approximately. In the first the differen...

One of the problems associated with photopolymers as optical recording media is the thickness variation during the recording process. Different values of shrinkages or swelling are reported in the literature for photopolymers. Furthermore, these variations depend on the spatial frequencies of the gratings stored in the materials. Thickness variatio...

A modified generalized, rational harmonic balance method is used to construct approximate frequency-amplitude relations for a conservative nonlinear singular oscillator in which the restoring force is inversely proportional to the dependent variable. The procedure is used to solve the nonlinear differential equation approximately. The approximate f...

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 solutions for the oscillator. To s...

Recently, we have proposed the application of interferometric techniques, both in transmission and in reflection, to characterize in real-time the modulation performance of the photopolymers. In this work we use this approach to characterize the optical modulation properties of a polyvinyl alcohol/acrylamide (PVA/AA) photopolymer. A double beam int...

We propose an alternative, direct method to calculate monomer diffusion times in photopolymer materials. Very long period gratings are recorded in the photopolymer, and the real time variation in diffraction efficiency due to monomer diffusion is then analyzed. In photopolymers, monomer diffusion plays a fundamental role in hologram formation. Howe...

We characterize the optical modulation properties of a polyvinyl alcohol∕acrylamide (PVA∕AA) photopolymer at the lowest end of recorded spatial frequencies. To achieve this goal we have constructed a double beam interferometer in combination with the setup to expose the recording material. This is a novel approach since usually holographic recordin...

We show an accurate procedure to obtain a Fourier transform (FT) with no dc term using a commercial twisted-nematic liquid-crystal display. We focus on the application to holographic storage of binary data pages, where a drastic decrease of the dc term in the FT is highly desirable. Two different codification schemes are considered: binary π radian...

We present the characterization and the optimization of the phase and amplitude modulation of a liquid crystal display (LCD) applied to holographic data storage. We discuss the main LCD modulation regimes demanded in the literature in the application to holographic memories: binary amplitude, binary phase and hybrid ternary modulation (HTM). We sho...

RESUMEN (ABSTRACT) Las titulaciones de Grado, en cumplimiento de las normativas del Espacio Europeo de Educación Superior, se separan en asignaturas básicas, obligatorias, y optativas. Según RD1393/2007 modificado por RD 861/2010, se tienen 60 ECTS de formación básica, dentro de los que se encuentra la materia de Física en la rama de Ingeniería y A...

The homotopy perturbation method is used to solve the nonlinear differential equation that governs the behaviour of a relativistic oscillator for which the nonlinearity (anharmonicity) is a relativistic effect due to the time line dilation along the world line. The approximate formulas obtained show excellent agreement with the exact solutions, and...

He's homotopy perturbation method is used to solve the nonlinear differential equation that governs the oscillations of a relativistic oscillator for which the nonlinearity (anharmonicity) is a relativistic effect due to the time line dilation along the world line. Unlike the usual non-relativistic harmonic oscillator, the velocity of the relativis...

This paper deals with the nonlinear oscillation of a simple pendulum and presents not only the exact formula for the period but also the exact expression of the angular displacement as a function of the time, the amplitude of oscillations and the angular frequency for small oscillations. This angular displacement is written in terms of the Jacobi e...

La implicació de l'alumnat en el procés d'ensenyament/aprenentatge (E/A) ha permés desenvolupar un conjunt d'accions per afavorir el treball autònom i el seu seguiment tutorial. S'ha oferit un compromís voluntari per a realitzar treballs presencials i no presencials (resolució de problemes) i el seguiment individual de les activitats planejades mit...

Este artigo aborda a oscilação não-linear de um pêndulo simples e apresenta não apenas a fórmula exata do período mas também a dependencia temporal do deslocamento angular para amplitudes das oscilações e a freqüência angular para pequenas oscilações. O deslocamento angular é escrito em termos da função elíptica de Jacobi sn(u;m) usando as seguinte...

El canvi de model educatiu que implica la integració del sistema universitari espanyol en l’Espai Europeu d’Educació Superior (EEES) implica centrar la docència en l’aprenentatge de l’alumnat. Per tant, com que una part important en aquest aprenentatge és el treball i l’esforç de l’alumnat, hem desenvolupat metodologies actives per afavorir-lo. En...

INTRODUCCIÓN La utilización de películas de corta duración sobre experimentos de Física presenta un gran potencial didáctico al poder los estudiantes visualizar fenómenos físicos explicados en las clases de teoría y realizados en el laboratorio. En este trabajo se presentan los resultados correspondientes a la grabación y posterior edición de exper...

RESUMEN En este trabajo proponemos un diseño curricular para las asignaturas de Física de primer curso correspondientes a los nuevos grados en Ingeniería y Arquitectura que se ofertarán en la Universidad de Alicante el curso 2010/2011. Nuestro diseño se centra en dos pilares fundamentales: el planteamiento de metodologías y materiales docentes adec...

We present a fruitful student's lab experiment allowing for an effective learning of some of the basics in physical optics. We proceed with the characterization of the surface structure of a compact disk (CD) and a digital versatile disk (DVD). This experiment is an effective means to have a direct hands-on experience on diffraction, Young's fringe...

El elevado nivel de suspensos y de alumnos no presentados a los exámenes de las asignaturas de Física de las titulaciones de la Escuela Politécnica Superior de la Universidad de Alicante, nos indujo, en el curso 2001/02 y 2002/03, a investigar las causas de tales resultados. El presente estudio, realizado a lo largo del curso 2003/2004, es la conti...

This article reports the findings of a diachronic study of acknowledgement practices in 300 randomly collected research papers published during three different periods (1998, 2004 and 2012) in the most prestigious American and European astrophysics journals written in English. In order to investigate the influence of these practices on authorship p...

Este trabajo ha sido financiado por el Vicerrectorado de Convergencia Europea y Calidad (convocatorio 2003) y por el Vicerrectorado de Tecnología e Innovación Educativa (convocatoria 2004) de la Universidad de Alicante.

La utilización de películas breves de experiencias prácticas de Física tiene un enorme potencial didáctico, ya que los estudiantes pueden visualizar - cuantas veces lo deseen- fenómenos físicos explicados teóricamente en el aula o realizados en las clases de laboratorio. Estas películas no sólo pueden hacer el proceso de aprendizaje más productivo,...

We are continuing a comprehensive systematic study of the properties of Wolf-Rayet (WR) galaxies based on data from ground and space observatories. In this proposal we request time on the KPNO 2.1m telescope to undertake CCD imagery and spectroscopy of a group of Northern WR galaxies. Our basic aim is threefold: identify and characterize the proper...

RESUMEN (ABSTRACT) La asignatura de Biomecánica de la Actividad Física es una asignatura básica en el Grado de Ciencias de Actividad Física y el Deporte. Esta asignatura en particular, recoge a un gran número de alumnos con perfil diferente, por ejemplo: alumnos con intensificación en letras o científico-técnico en sus estudios de bachiller, alumno...

In this work we study the capabilities of the PVA/AA based photopolymers to record diffractive optical elements (DOEs). A double beam interferometer is constructed, both in transmission and in reflection, in combination with the setup to expose the recording material. Some benefits are provided by this approach: direct calculation of the properties...

Este trabajo ha sido financiado por el Ministerio de Educación y Ciencia a través de los proyectos FIS2005-05881-C01-01 y FIS2005-05881-C01-02, por la Generalitat Valenciana, proyecto GV06-007 y por la Universidad de Alicante, proyecto GRE04-06.

In this work we show how liquid crystal displays can be a useful tool to introduce amplitude and phase concepts to students. Amplitude and phase play a very important role in the description of wave related phenomena, basic in many fields of Science and Engineering. Phase information is usually less evident than amplitude information since it is no...

Phase-only modulation using liquid crystal displays (LCDs) is very interesting for many applications (optical signal processing, holographic data storage, ...), however, in general they offer a limited phase modulation depth. In this paper we show various alternatives in order to enhance the phase modulation depth. This work was supported by the "M...

Liquid crystal displays (LCDs) have found widespread use in many areas in optics where spatial light modulation is necessary. In this paper we explore a novel application, where the LCD is used as the master to generate diffractive optical elements onto a photopolymer. This work was supported by the "Ministerio de Educación y Ciencia", Spain (proje...

En el ámbito de los créditos ECTS, el trabajo que presentamos tiene como base la implementación de metodologías de trabajo durante dos semanas, no con conocimientos nuevos, sino con competencias adquiridas y necesarias para comprender los objetivos de la titulación, específicamente impartidos en las asignaturas de Física. La idea es obtener una val...

Since academic year 2003/2004 a series of modifications has been introduced in physics subjects of the Engineering degrees of the University of Alicante in order to achieve a continuous evaluation. The importance of continuous evaluation increases the students’ success, in particular in experimental subjects, where the level of abstraction needed f...

Comunicación presentada en la IV Jornada de Innovación Tecnológico Educativa, Alicante, 6 de Febrero de 2007, Universidad de Alicante.