Constant rate thermal analysis for thermal stability studies of polymers

This paper explores the relationship between the shapes of temperature-time curves obtained from experimental data recorded by means of constant rate thermal analysis (CRTA) and the kinetic model followed by the thermal degradation reaction. A detailed shape analysis of CRTA curves has been performed as a function of the most common kinetic models. The analysis has been validated with simulated data, and with experimental data recorded from the thermal degradation of polytetrafluoroethylene (PTFE), poly(1,4-butylene terephthalate) (PBT), polyethylene (PE) and poly(vinyl chloride) (PVC). The resulting temperature-time profiles indicate that the studied polymers decompose through phase boundary, random scission, diffusion and nucleation mechanisms respectively. The results here presented demonstrate that the strong dependence of the temperature-time profile on the reaction mechanism would allow the real kinetic model obeyed by a reaction to be discerned from a single CRTA curve.Junta de Andalucía TEP-03002Ministerio de Ciencia e Innovación MAT 2008-06619/MA

Angiolymphoid hyperplasia involving large arteries

Angiolymphoid hyperplasia with eosinophilia (ALHE) is a rare vascular proliferative disorder, which most commonly involves the skin of the head and neck regions. Noncutaneous localization of this pathology is unusual, and its primary localization in large arteries presenting as a pulsatile mass is extremely rare. We report here two cases of ALHE manifested as masses of the occipital and brachial artery. ALHE should be considered in the differential diagnosis of localized peripheral arterial masses in young patients

Evaluation of alfalfa varieties in the province of Salamanca

XLV Reunión Científica de la SEEP (Sesión: Producción Vegetal)Se realiza un estudio comparativo de 26 variedades registradas de alfalfa (Medicago sativa L.), cultivadas en regadío en la provincia de Salamanca, evaluando la producción y contenido de proteína bruta. El primer año del experimento se realizaron cuatro cortes, siendo la producción en el primer corte significativamente más baja que en el resto. La producción total anual oscila entre 8160 kg ha-1 en la variedad “Baraka” y 10109 kg ha-1 en “Bar MS 82439”, con un valor medio sobre todas las variedades de 9370 kg ha-1. El contenido de proteína bruta oscila entre 19,30% en la variedad “Almar” y 23,47% en la variedad “Aragón”.{ENG}Dry matter production and protein content were evaluated in 26 alfalfa (Medicago sativa L.) varieties grown under irrigation in the province of Salamanca. In the first year four harvests were made. The dry matter production of the first haverst was the lowest. The annual dry matter production ranged between 8160 kg ha-1 in “Baraka” and 10109 kg ha-1 in “Bar MS 82439”, with a mean value across varieties of 9370 kg ha-1. The protein content ranged between 19.30% in “Almar” and 23.47% in “Aragón” variety.Este trabajo ha sido realizado con financiación del Ministerio de Ciencia y Tecnología (AGL2002-02766 AGR-FOR

Dependence of the preexponential factor on temperature

The dependence of the preexponential factor on the temperature has been examined and the errors involved in the activation energy calculated from isothermal and non-isothermal methods without considering such dependence have been estimated. It has been shown that the error in the determination of the activation energy calculated ignoring the dependence of Aon Tcan be rather large and it is dependent on x=E/RT, but independent of the experimental method used. It has been also shown that the error introduced by omitting the dependence of the preexponential factor on the temperature is considerably larger than the error due to the Arrhenius integral approach used for carrying out the kinetic analysis of TG data.Peer reviewe

Mediación semántica A* basada en MDE para la generación de arquitecturas en tiempo de ejecución

Existen aplicaciones software que necesitan ser adaptadas en tiempo de ejecución debido a que los componentes que conforma su arquitectura no representan la configuración óptima. En estos casos, las arquitecturas deben ser reconfiguradas, por ejemplo, añadiendo y eliminando componentes, o modificando las relaciones entre ellos. Este artı́culo presenta una propuesta para la generación de arquitecturas en tiempo de ejecución. Está enfocado en la descripción del proceso que ocurre desde que existe una definición de arquitectura que hay que resolver, hasta que se genera la mejor configuración que da solución a dicha arquitectura. Para construir dicha configuración, se utilizan técnicas de modelado, mecanismos de trading y un algoritmo de búsqueda A*. Dicho algoritmo hace uso de una heurı́stica basada en la información sintáctica y semántica de los componentes. Como dominio de aplicación, se muestra un caso estudio para la generación de interfaces de usuario

Área efectiva de radiación (Sd) para un pistón axisimétrico radiando en un plano infinito

El cálculo exacto y la determinación experimental del Área de Efectiva de Radiación (Sd) siempre ha sido un tema sumamente importante para establecer los parámetros del altavoz. Incluso si el Integral de Rayleigh de difracción se puede utilizar para evaluar la presión sonora en cualquier punto, es muy difícil obtener un valor preciso para el Sd, debido a la solución de la integral de superficie. En este trabajo, proponemos un método simplificad usando herramientas computacionales y la simetría cilíndrica en la mayoría de los pistones, con el fin de reducir las dificultades matemáticas. Entonces, las soluciones para diferentes tipos de pistón se comparan con otras obtenidas en diferentes enfoques experimentales con el fin de analizar la precisión de este nuevo enfoque.Tesi

Multi-person 3D pose estimation from unlabelled data

Its numerous applications make multi-human 3D pose estimation a remarkably impactful area of research. Nevertheless, assuming a multiple-view system composed of several regular RGB cameras, 3D multi-pose estimation presents several challenges. First of all, each person must be uniquely identified in the different views to separate the 2D information provided by the cameras. Secondly, the 3D pose estimation process from the multi-view 2D information of each person must be robust against noise and potential occlusions in the scenario. In this work, we address these two challenges with the help of deep learning. Specifically, we present a model based on Graph Neural Networks capable of predicting the cross-view correspondence of the people in the scenario along with a Multilayer Perceptron that takes the 2D points to yield the 3D poses of each person. These two models are trained in a self-supervised manner, thus avoiding the need for large datasets with 3D annotations

Contabilidad y cobros de rentas en la Santa Capilla de San Andrés de Jaén. Dos siglos y medio tras la búsqueda de la eficiencia (1650-1900). (Accounting and income collection at the Santa Capilla de San Andrés in Jaén. Two and a half centuries in search of efficiency (1650-1900).

La Santa Capilla de San Andrés de Jaén es una institución benéfica que tiene sus orígenes en 1515 y aún pervive. Su contabilidad, establecida para la rendición de cuentas por parte del receptor, se sustentó en el método de cargo y data y en diversos libros necesarios, tales como los de hacienda, de gastos de meses o el cuaderno de no cobrados. En este trabajo, sobre la base del análisis de la enorme cantidad de datos que suministran sus cuentas entre 1650 y 1900, hemos estudiado la función de cobro de rentas del receptor y la eficiencia en el desempeño de la misma, así como la legitimación conseguida por los principales promotores de cambios en orden a su mejora. The Santa Capilla de San Andrés in Jaén is a charity institution founded in 1515 that still functions. Its accounting system was established to take the accounts to the receptor or collector. The accounting was performed by the Charge and Discharge method and besides the main book of this method it was also supported by several books, such as the book of the hacienda, the monthly expenses book and the booklet of outstanding income. In this paper, we have studied the collection function performed by the receptor on the basis of the huge amount of data provided by the account books regarding the period 1650-1900. By fulfilling this task we have devoted special attention to the efficieny with which the collection function was performed, as well as to the changes introduced to improve it and the success met in this process.Contabilidad eclesiástica, método de cargo y data, administración de rentas. Ecclesiastical accounting, Charge and Discharge method, income management.

Limitations of model-fitting methods for kinetic analysis: Polystyrene thermal degradation

In this paper, some clarifications regarding the use of model-fitting methods of kinetic analysis are provided in response to the lack of plot linearity and dispersion in the activation energy values for the thermal degradation of polystyrene found in the literature and some results proposing an nth order model as the most suitable one. In the present work, two model-fitting methods based on the differential and integral forms of the general kinetic equation are evaluated using both simulated and experimental data, showing that the differential method is recommended due to its higher discrimination power. Moreover, the intrinsic limitations of model-fitting methods are highlighted: the use of a limited set of kinetic models to fit experimental data and the ideal nature of such models. Finally, it is concluded that a chain scission model is more appropriate than first order. © 2013 Elsevier B.V.Peer Reviewe