Vigas de pino silvestre sometidas a flexión : influencia de defectos y singularidades = Wild pine beams subjected to bending : influence of defects and singularities

This paper presents an experimental study of the behavior of 18 timber beams for structural use of 155x75x1090mm dimensions. The origin of the wood is Valsaín sawmill. The tests were performed at the Laboratory of Construction Materials at the University School of Technical Architecture. The objective of this work is the analysis of flexural behavior of test pieces according to the defects and singularities, carrying out an analysis of their influence. 18 pieces have been tested, of which 9 were placed in a flat position, and the other 9 were placed in edge position. Before testing, the samples were classified according to UNE 56544 visual grading of sawn timber for structural use, determining the structural quality of each piece and the strength class. Singularities and defects found in each one of the pieces, moisture, weight and dimensions are measured and identified. The results of the analysis are presented in the conclusions, comparing the test data with the characteristics of the beams, determining the influence of the presence of defects and the characteristics of the timber beams with resistance in tests

Bending reinforcement of timber beams with composite carbon fiber and basalt fiber materials

En el presente trabajo se lleva a cabo un estudio basado en datos obtenidos experimentalmente mediante el ensayo a flexión de vigas de madera de pino silvestre reforzadas con materiales compuestos. Las fibras que componen los tejidos utilizados para la ejecución de los refuerzos son de basalto y de carbono. En el caso de los compuestos de fibra de basalto se aplican en distintos gramajes, y los de carbono en tejido unidireccional y bidireccional. El material compuesto se realizó in situ, simultáneamente a la ejecución del refuerzo. Se aplicaron en una y en dos capas, según el caso, y la forma de colocación fue en ?U?, adhiriéndose al canto inferior y a las caras laterales de la viga mediante resina o mortero epoxi. Se analiza el comportamiento de las vigas según las variables de refuerzo aplicadas y se comparan con los resultados de vigas ensayadas sin reforzar. Con este trabajo queda demostrado el buen funcionamiento del FRP de fibra de basalto aplicado en el refuerzo de vigas de madera y de los tejidos de carbono bidireccionales con respecto a los unidireccionales

Estudio de la resistencia de vigas de madera reforzadas con FRP de tejidos unidireccionales y bidireccionales de fibra de carbono

En este trabajo se realiza un estudio experimental del comportamiento de veinte vigas de madera aserrada de pino silvestre para uso estructural, de dimensiones 155x75x1090mm y reforzadas con materiales compuestos de fibra de carbono. La procedencia de la madera es el aserradero de Valsaín. Los ensayos se han realizado en el Laboratorio de Materiales de Construcción de la Escuela Universitaria de Arquitectura Técnica de Madrid con una máquina de ensayos Universal. El objetivo del trabajo es el análisis del comportamiento a flexión de las piezas ensayadas reforzadas con materiales compuestos de fibra de carbono realizados con tejidos unidireccionales y bidireccionales. De las veinte vigas ensayadas nueve fueron sin reforzar y el resto se reforzaron con el refuerzo en forma de ?U?, adhiriendo el material compuesto a la cara inferior y los laterales de las vigas, hasta una altura de la mitad del canto. Para la realización de los FRP se han empleado tejidos de fibra de carbono unidireccionales y bidireccionales. El gramaje de los tejidos unidireccionales es de 300gr/m2 y se ha aplicado en una capa. Los tejidos bidireccionales utilizados tienen dos gramajes distintos, 160gr/m2 y 210gr/m2. Éstos últimos se han aplicado en una y en dos capas. Las nueve vigas ensayadas sin reforzar han servido como testigo para analizar el aumento de la capacidad de carga de las vigas reforzadas. A partir de los datos facilitados por el software se asociado a la máquina de ensayos se trazaron los gráficos carga-desplazamiento, con el fin de analizar las cargas máximas de rotura alcanzadas, desplazamientos y rigidez de las piezas. Posteriormente se realiza un análisis analítico hallando los valores medio de las cargas de rotura y los desplazamientos, realizando una comparación entre los datos obtenidos para las vigas sin reforzar y las reforzadas con los distintos sistemas. En las conclusiones se presentan los resultados del análisis realizado, estudiando el incremento de la capacidad de carga de las vigas reforzadas con respecto a las no reforzadas, y comparando entre sí el funcionamiento de los refuerzos aplicados

MAP entropy estimation: applications in robust image filtering

We introduce a new approach for image filtering in a Bayesian framework. In this case the probability density function (pdf) of thelikelihood function is approximated using the concept of non-parametric or kernel estimation. The method is based on the generalizedGaussian Markov random fields (GGMRF), a class of Markov random fields which are used as prior information into the Bayesian rule, whichprincipal objective is to eliminate those effects caused by the excessive smoothness on the reconstruction process of images which arerich in contours or edges. Accordingly to the hypothesis made for the present work, it is assumed a limited knowledge of the noise pdf,so the idea is to use a non-parametric estimator to estimate such a pdf and then apply the entropy to construct the cost function for thelikelihood term. The previous idea leads to the construction of Maximum a posteriori (MAP) robust estimators, since the real systems arealways exposed to continuous perturbations of unknown nature. Some promising results of three new MAP entropy estimators (MAPEE) forimage filtering are presented, together with some concluding remarks

Sexual dimorphism: a comparative study between inhabitants from El Hierro and other populations of the Word.

Sex estimation based on tibial measurements can be achieved using discriminant functions combining several parameters. However, functions differ from one population to another, because sexual dimorphism may be more or less marked among different ancestry or ethnic groups. Calculation of one of these functions with the dimensions of populations other than that from which the function was obtained may misclassify a different proportion of males or females than when calculated with the dimensions of the original population. By dividing the proportions of correctly classified individuals when the function was applied to the population from which it derived and that of El Hierro (Canary Islands), we can calculate an index of male trait expression and an index of female trait expression, and, by addition of both indices, an index of sexual dimorphism. Therefore, it is possible to compare the degree of sexual dimorphism among several populations, at least regarding those measurements included in the function. Based on this fact we have calculated several functions (reported in the scientific literature), obtained from tibiae of modern black, white, and Japanese populations, and from medieval Croatians and prehispanic inhabitants of Gran Canaria (ap. 1000 BP), with the dimensions of the prehispanic population of El Hierro, genetically sexed, also with an antiquity of ap. 1000 BP. Despite the different antiquity, the population of El Hierro was more dimorphic that the modern Japanese one, but less dimorphic than most of the other groups with which it was compared, especially when functions including distal epiphyseal breadth and minimum shaft perimeter (near the distal end of the tibiae) were calculated: in these cases, dimorphism was lower for the population of El Hierro, due to the fact that, although male trait expression index was higher, many females of El Hierro were misclassified as males because of the abnormally thick distal diaphyseal and epiphyseal breadths of El Hierro inhabitants

An alternative approach to the tomographic reconstruction of smooth refractive index distributions

Continuous, mathematically smooth Phase Objects with radial symmetry are reconstructed from cross sections of their refractive index distribution by a novel method, consisting of a linear combination of Gaussian basis functions, whose technical details are discussed. As an application example, this approach is used to get a fast and accurate estimation of the temperature distribution of an actual soldering tip

An alternative method for phase-unwrapping of interferometric data

In this paper we present a novel algorithm for phase unwrapping where only a subset of data from the wrapped phase map is used to reconstruct the unwrapped phase map as a linear combination of radial basis functions (RBF’s). For noisy phase maps this algorithm gives better results than three reference algorithms based on radial basis functions, Zernike polynomials and path dependent phase unwrapping strategies

The QUIJOTE TGI

The QUIJOTE TGI instrument is currently being assembled and tested at the IAC in Spain. The TGI is a 31 pixel 26-36 GHz polarimeter array designed to be mounted at the focus of the second QUIJOTE telescope. This follows a first telescope and multi-frequency instrument that have now been observing almost 2 years. The polarimeter design is based on the QUIET polarimeter scheme but with the addition of an extra 90º phase switch which allows for quasiinstantaneous complete QUI measurements through each detector. The advantage of this is a reduction in the systematics associated with differencing two independent radiometer channels. The polarimeters are split into a cold front end and a warm back end. The back end is a highly integrated design by engineers at DICOM. It is also sufficiently modular for testing purposes. In this presentation the high quality wide band components used in the optical design (also designed in DICOM) are presented as well as the novel cryogenic modular design. Each polarimeter chain is accessible individually and can be removed from the cryostat and replaced without having to move the remaining pixels. The optical components work over the complete Ka band showing excellent performance. Results from the sub unit measurements are presented and also a description of the novel calibration technique that allows for bandpass measurement and polar alignment. Terrestrial Calibration for this instrument is very important and will be carried out at three points in the commissioning phase: in the laboratory, at the telescope site and finally a reduce set of calibrations will be carried out on the telescope before measurements of extraterrestrial sources begin. The telescope pointing model is known to be more precise than the expected calibration precision so no further significant error will be added through the telescope optics. The integrated back-end components are presented showing the overall arrangement for mounting on the cryostat. Many of the microwave circuits are in-house designs with performances that go beyond commercially available products. Individual component performance is be presented showing for each of the sub modules

QUIJOTE-CMB experiment: a technical overview

The QUIJOTE-CMB experiment (Q-U-I JOint TEnerife CMB experiment) is an ambitious project to obtain polarization measurements of the sky microwave emission in the 10 to 47 GHz range. With this aim, a pair of 2,5m telescopes and three instruments are being sited at the Teide Observatory, in Tenerife (Canary Islands, Spain). The first telescope and the first instrument (the MFI: Multi Frequency Instrument) are both already operating in the band from 10 to 20 GHz, since November 2012. The second telescope and the second instrument (TGI: Thirty GHz instrument) is planned to be in commissioning by the end of summer 2014, covering the range of 26 to 36 GHz. After that, a third instrument named FGI (Forty GHz instrument) will be designed and manufactured to complete the sky survey in the frequency range from 37 to 47 GHz. In this paper we present an overview of the whole project current status, from the technical point of view