Time resolved pattern evolution in a large aperture laser

We have measured quasi-instantaneous transverse patterns in a broad aperture laser. Non-ordered patterns yielding to boundary determined regular structures in progressive time-integrated recording are observed. The linear analysis and numerical integration of the full Maxwell-Bloch equations allow us to interpret the features of the experiment. We show that this system being far from threshold cannot be fully understood with a perturbative model.Comment: 7 pages, 5 GIF figures . To be published in Phys. Rev. Let

Determination of the energy behaviour in municipalities with fewer than 6000 inhabitants in Badajoz (Spain)

La mayoría de los municipios de Europa tienen una población de menos de 6000 habitantes y un alto consumo de energía. Para reducir el consumo, es necesario conocer de antemano el comportamiento energético de un municipio. El objetivo de este artículo es analizar la situación energética y medioambiental de los municipios de la provincia de Badajoz (España) y formular indicadores de eficiencia energética y medioambiental. El método se basa en el análisis de 74 auditorías energéticas realizadas entre 2012 y 2014 en los municipios correspondientes, y se estudia el consumo medio de energía final en función de cuatro variables diferentes: superficie del municipio, número de habitantes, coste de la energía y emisiones anuales de CO2. Además, se realizó un análisis estadístico basado en se llevó a cabo una variación. Los resultados obtenidos muestran que el consumo energético anual medio de un municipio de menos de 6000 habitantes es de 300 kWh por habitante y 1 kWh por m2 de superficie. Se observó una gran variabilidad en el costo medio de la energía para cada municipio, entre 0,11 y 0,25 /kWh, con una media de 0,17 /kWh. Además, por métodos estadísticos se determinó que el consumo de energía de un municipio es proporcional a la superficie que ocupa y a su número de habitantes, proponiendo una ecuación que permite determinar el consumo final de energía según ambas variables. Este benchmarking es válido para implementar técnicas de ahorro energético y para priorizar las inversiones en la renovación de las instalaciones. No existen precedentes de estudios de investigación similares con un número tan elevado de municipios.Most of the municipalities in Europe have a population of less than 6000 inhabitants and high energy consumption. In order to reduce consumption, it is necessary to know the energy behaviour of a municipality beforehand. The purpose of this article is to analyse the energy and environmental situation of the municipalities of the province of Badajoz (Spain) and formulates energy efficiency and environmental indicators. The method is based in the analysis of 74 energy audits were carried out between 2012 and 2014 in the corresponding municipalities, and the average final energy consumption was studied in terms of four different variables: area of the municipality, number of inhabitants, cost of energy, and annual CO2 emissions. In addition, a statistical analysis based on variance was carried out. The results obtained show that the average annual energy consumption of a municipality of less than 6000 inhabitants is 300 kWh per inhabitant and 1 kWh per m2 of surface area. A great variability was observed in the average cost of energy for each municipality, between 0.11 and 0.25 /kWh, with an average of 0.17 /kWh. In addition, by statistical methods it was determined that the energy consumption of a municipality is proportional to the surface área that it occupies and its number of inhabitants, proposing an equation that allows determining the final energy consumption according to both variables. This benchmarking is valid to implement energy saving techniques and to prioritize investments in the renovation of the facilities. There are no precedents of similar research studies with such a large number of municipalities.• Programa de Cooperación Transfronteriza España y Portugal (POCTEP) y Fondos FEDER. Proyecto europeo RED URBANSOLpeerReviewe

Modelo de evaluación de la gestión logística en empresas

Diversos estudios apuntan a que el desarrollo de cualquier área de gestión empresarial requiere tanto de la existencia de sistemas de gestión para los procesos implicados, como de modelos de evaluación y diagnóstico basados en su correspondiente sistema de gestión. En el área de la gestión logística, la literatura científica y diversos trabajos técnicos ya recogen la existencia de un sistema de gestión logística (modelo CPLA). Por tanto, este trabajo desarrolla un modelo de evaluación basado en el modelo CPLA de gestión logística, contando además con la experiencia de aplicación en más de 30 empresas de diversos sectores industriales

Complete spatial characterization of a pulsed doughnut-type beam by use of spherical optics and a cylindrical lens

A complete spatial characterization (in second-order moments) of a doughnut-type beam from a pulsed transversely excited atmospheric CO_2 laser is described. It includes the measurement of the orbital angular momentum carried by the beam. The key element in the characterization is the use of a cylindrical lens in addition to the usual spherical optics. Internal features of the beam that would have remained hidden if only spherical optics were employed were revealed by use of the cylindrical lens. The experimental results are compared and agree with a theoretical Laguerre-Gauss mode bea

Synthesis of the BCDE Molecular Fragment of Azadiradione Mediated by Titanocene(III)

[EN]A practical, short, and diastereoselective synthesis of the azadiradione BCDE fragment from a readily available starting material is described. The key step was the titanocene(III)-promoted tandem cyclization of unsaturated epoxy nitrile

Time-resolved spatial structure of TEA CO_2 laser pulses

The evolution of the intensity profile of TEA CO_2 laser pulses along the pulse length is investigated both analytically and experimentally. A simple scalar model of the pulse amplitude is introduced, which gives the loaded-cavity modes as a linear combination of bidimensional Hermite-Gauss functions. According to this model a number of equations are derived which link the time-varying spatial structure of the pulse to its time-resolved second-order intensity moments, namely, the beam width and the M^2 parameter

Probabilistic Approach to Pattern Selection

The problem of pattern selection arises when the evolution equations have many solutions, whereas observed patterns constitute a much more restricted set. An approach is advanced for treating the problem of pattern selection by defining the probability distribution of patterns. Then the most probable pattern naturally corresponds to the largest probability weight. This approach provides the ordering principle for the multiplicity of solutions explaining why some of them are more preferable than other. The approach is applied to solving the problem of turbulent photon filamentation in resonant media.Comment: LaTex, 22 page

Spatial characterization of the transversal structure of rotationally symmetric pulsed beams

A simple analytical model is proposed to describe the transversal spatial structure of a tridimensional rotationally symmetric pulsed beam. The spatial behaviour of the pulse amplitude is shown to be linked to its (measurable) second- and higher-order intensity moments, namely, beam width, quality parameter and kurtosis. As an illustrative experimental example, this model has been applied to high-quality TEA CO_2 laser pulse

Time-varying beam quality factor and mode evolution in TEA CO_2 laser pulses

The time evolution of the transversal modes in a TEA CO_2 laser cavity has been investigated from the analysis of the time-varying beam quality factor M^2 of the emitted pulses. The experiments reveal a significant change in this parameter during the pulse evolution, which can be translated into an evolution of the modes of the laser cavity to reach a nearly stationary behavior. Attention is focused on both the appearance of a particular mode and the duration of its growing process