Analysis of the Fracture of Reinforced Concrete Flat Elements Subjected to Explosions. Experimental Procedure and Numerical Validation

Many of the material models most frequently used for the numerical simulation of the behavior of concrete when subjected to high strain rates have been originally developed for the simulation of ballistic impact. Therefore, they are plasticity-based models in which the compressive behavior is modeled in a complex way, while their tensile failure criterion is of a rather simpler nature. As concrete elements usually fail in tensión when subjected to blast loading, available concrete material models for high strain rates may not represent accurately their real behavior. In this research work an experimental program of reinforced concrete fíat elements subjected to blast load is presented. Altogether four detonation tests are conducted, in which 12 slabs of two different concrete types are subjected to the same blast load. The results of the experimental program are then used for the development and adjustment of numerical tools needed in the modeling of concrete elements subjected to blast.

Simplified Procedure for the Nonlinear Seismic Analysis of Bridges

The severe accidents suffered by bridges during recent earthquake show that more careful analysis are needed to guarantee their behaviour. In particular simplified non-linear analysis could be useful to bridge the gap between theoretical research and practical applications. This paper presents one of those simplified methods that can be applied for first designs or to retrofitting of groups of bridges.

A robust procedure for damage detection from strain measurements based on principal component analysis

FBGs are excellent strain sensors, because of its low size and multiplexing capability. Tens to hundred of sensors may be embedded into a structure, as it has already been demonstrated. Nevertheless, they only afford strain measurements at local points, so unless the damage affects the strain readings in a distinguishable manner, damage will go undetected. This paper show the experimental results obtained on the wing of a UAV, instrumented with 32 FBGs, before and after small damages were introduced. The PCA algorithm was able to distinguish the damage cases, even for small cracks. Principal Component Analysis (PCA) is a technique of multivariable analysis to reduce a complex data set to a lower dimension and reveal some hidden patterns that underlie.

Procedure for verification of sound source coverage over façades according to the International Standard ISO 140-5

This paper presents a new verification procedure for sound source coverage according to ISO 140?5 requirements. The ISO 140?5 standard applies to the measurement of façade insulation and requires a sound source able to achieve a sufficiently uniform sound field in free field conditions on the façade under study. The proposed method involves the electroacoustic characterisation of the sound source in laboratory free field conditions (anechoic room) and the subsequent prediction by computer simulation of the sound free field radiated on a rectangular surface equal in size to the façade being measured. The loudspeaker is characterised in an anechoic room under laboratory controlled conditions, carefully measuring directivity, and then a computer model is designed to calculate the acoustic free field coverage for different loudspeaker positions and façade sizes. For each sound source position, the method provides the maximum direct acoustic level differences on a façade specimen and therefore determines whether the loudspeaker verifies the maximum allowed level difference of 5 dB (or 10 dB for façade dimensions greater than 5 m) required by the ISO standard. Additionally, the maximum horizontal dimension of the façade meeting the standard is calculated and provided for each sound source position, both with the 5 dB and 10 dB criteria. In the last section of the paper, the proposed procedure is compared with another method used by the authors in the past to achieve the same purpose: in situ outdoor measurements attempting to recreate free field conditions. From this comparison, it is concluded that the proposed method is able to reproduce the actual measurements with high accuracy, for example, the ground reflection effect, at least at low frequencies, which is difficult to avoid in the outdoor measurement method, and it is fully eliminated with the proposed method to achieve the free field requisite.

A FEM-BEM coupling procedure through the Steklov-Poincarè operator

Many advantages can be got in combining finite and boundary elements.It is the case, for example, of unbounded field problems where boundary elements can provide the appropriate conditions to represent the infinite domain while finite elements are suitable for more complex properties in the near domain. However, in spite of it, other disadvantages can appear. It would be, for instance, the loss of symmetry in the finite elements stiffness matrix, when the combination is made. On the other hand, in our days, with the strong irruption of the parallel proccessing the techniques of decomposition of domains are getting the interest of numerous scientists. With their application it is possible to separate the resolution of a problem into several subproblems. That would be beneficial in the combinations BEM-FEM as the loss of symmetry would be avoided and every technique would be applicated separately. Evidently for the correct application of these techniques it is necessary to establish the suitable transmission conditions in the interface between BEM domain and FEM domain. In this paper, one parallel method is presented which is based in the interface operator of Steklov Poincarè.

Identification procedure of mealy apples by instrumental means. Extraction of storage features.

Mealiness is a negative attribute of sensory texture that combines the sensation of a disaggregated tissue with the sensation of lack of juiciness. Since January 1996, a wide EC Project entitled : "Mealiness in fruits. Consumers perception and means for detection'" is being carried out. Within it, three sensory panels have been trained at : the Institute of Food Research (IFR, United Kingdom), the Instituto de Agroquímica y Tecnología de los Alimentos (IATA, Spain) and the Institut voor Agrotechnologisch Onderzoek (ATO-DLO, Netherlands) to assess mealiness in apples. In all three cases, mealiness has been described as a multidimensional sensory descriptor capable of gathering the loss of consistency (of crispness and of hardness) and of juiciness. Also within the EC Project several instrumental procedures have been tested for mealiness assessment. In this sense the Physical Properties Laboratory (ETS1A-UPM) has focused its aims in a first stage on performing instrumental tests for assessing some textural descriptors as crispiness, hardness and juiciness. The results obtained within these tests have shown to correlate well with the sensory measurements (Barreiro et Ruiz-Altisent, 1997) in apples, but also have succeed when trying to generate several texture degradation levels on peaches from which mealiness appears to be the last stage (Ortiz et al. 1997).

A procedure for testing padding materials in fruit packing lines.

Padding materials are commonly used in fruit packing lines with the objective of diminishing impact damage in postharvest handling. Two sensors, instrumented sphere IS 100 and impact tester, have been compared to analyze the performance of six different padding materials used in Spanish fruit packing lines. Padding materials tested have been classified according to their capability to decrease impact intensities inflicted to fruit in packing lines. A procedure to test padding materials has been developed for "Golden" apples. Its basis is a logistic regression to predict bruise probability in fruit. The model combines two kinds of parameters: padding material parameters measured with IS, and fruit properties.

A new procedure for race analysis in swimming based on individual distance measurements

biomecanica de la natación

LED bulb lamps technical specification and testing procedure for solar home systems.

With the consolidation of the new solid state lighting LEOs devices, te5t1n9 the compliance 01 lamps based on this technology lor Solar Home Systems (SHS) have been analyzed. The definition of the laboratory procedures to be used with final products 15 a necessary step in arder to be able to assure the quality of the lamps prior to be installed [1]. As well as with CFL technology. particular attention has been given to simplicity and technical affordability in arder to facilitate the implementation of the test with basie and simple laboratory too15 even on the same SHS electrification program locations. The block of test procedures has been applied to a set of 14 low-cost lamps. They apply to lamp resistance, reliability and performance under normal, extreme and abnormal operating conditions as a simple but complete quality meter tool 01 any LEO bulb.

Quantification of impacts in artistic gymnastics with accelerometry: an approximation

Intensity and volume of training in Artisti Gymnastics are increasing as the sooner athlete's age of incorporation creating some disturbance in them.

LED bulbs technical specification and testing procedure for solar home systems

The definition of technical specifications and the corresponding laboratory procedures are necessary steps in order to assure the quality of the devices prior to be installed in Solar Home Systems (SHS). To clarify and unify criteria a European project supported the development of the Universal Technical Standard for Solar Home Systems (UTSfSHS). Its principles were to generate simple and affordable technical requirements to be optimized in order to facilitate the implementation of tests with basic and simple laboratory tools even on the same SHS electrification program countries. These requirements cover the main aspects of this type of installations and its lighting chapter was developed based on the most used technology at that time: fluorescent tubes and CFLs. However, with the consolidation of the new LED solid state lighting devices, particular attention is being given to this matter and new procedures are required. In this work we develop a complete set of technical specifications and test procedures that have been designed within the frame of the UTSfSHS, based on an intense review of the scientific and technical publications related to LED lighting and their practical application. They apply to lamp reliability, performance and safety under normal, extreme and abnormal operating conditions as a simple but complete quality meter tool for any LED bulb.

Contextualización teórica del acto pedagógico en la enseñanza y el aprendizaje del proyecto arquitectónico: el caso de la E.T.S.A.M.

El taller de proyectos constituye el núcleo de la enseñanza arquitectónica. Estudiar sus procesos educativos en la actualidad implica la contextualización teórica del acto educativo y la revisión histórica de la evolución de su estructura social. Esta estructura, es heredera de la larga tradición del taller donde los maestros de obra, artesanos, arquitectos y artistas, se ocupaban desde siempre de la enseñanza de la construcción, de la artesanía, del diseño arquitectónico y del arte. Los aprendices se sometían a la autoridad de sus maestros y pasaban horas practicando, produciendo y aprendiendo junto a ellos. Con la aparición de las primeras Academias de arte y posteriormente de arquitectura, se evidenció un progresivo interés de los Estados hacía los productos artísticos y arquitectónicos. La consideración de las artes y de la arquitectura como proyecto estatal, supuso la construcción lenta, pero consolidable, de un proyecto educativo paralelo, coexistiendo simultáneamente con los talleres de los maestros, pero sin posibilidad de integración, hasta mucho más tarde. La “teoría”, que es de lo que se ocupaba la academia, con la “práctica” que es lo que se desarrollaba en el taller, no encontraban fácilmente la manera de encajarse y complementarse mutuamente en un proyecto educativo común. Las concepciones educativas de ambos, afrontaban la enseñanza y el aprendizaje desde puntos de vista también diferentes; mientras la Academia representaba el conocimiento validado y explicitado, en el taller se trabajaba con un conocimiento tácito e implícito. En la práctica artística del taller era donde se producía el aprendizaje mientras que en la Academia es donde se validaba. Esta estructura llegó en muchas ocasiones a situaciones extremas, no siendo casual que las más grandes crisis registradas en la historia de la enseñanza de las artes, coincidieran con un aumento de la distancia entre estas dos “instituciones”, talleres y academias. Por otra parte, parece que cualquier proyecto o concepto innovador, se ha fundado sobre la redistribución de estos equilibrios perdidos. En dicho contexto, en el campo de la educación y especialmente en el siglo XX, surge un debate que se estructura en base a los fines de la educación, contemplando dos posturas bien diferenciadas. Una de ellas sostiene como fin primordial de la educación, el desarrollo de la conciencia y la reciprocidad social del individuo. La otra, fija como fin el desarrollo de su singularidad. La búsqueda del equilibrio entre ambas, parte del interés por fomentar el crecimiento de lo que cada ser humano posee de individual, armonizándolo con la unidad orgánica del grupo social al que pertenece (Read 2010, 33). Sobre esta tensión se han basado muchos de los discursos pedagógicos y especialmente los aquí usados. La estructura social en los talleres de proyectos arquitectónicos, presenta hoy día una máxima integración entre las dos instituciones, el taller y la Academia, tanto a nivel del espacio, donde tiene lugar la enseñanza, como a nivel conceptual y pedagógico. Los talleres de proyectos poseen un formato de enseñanza y aprendizaje que constituye un paradigma (Schön, 2008) no solo dentro, sino también fuera del campo arquitectónico. Bajo este formato se complementa el aprendizaje práctico con el teórico y la producción, con la validación del conocimiento. Aunque tal estructura pedagógica presenta importantes variaciones entre unas escuelas de arquitectura y otras, los principales procesos que tienen lugar, son lo suficientemente similares, como para poder ser examinados desde una perspectiva común. Esta investigación, estudia el taller de proyectos desde un aspecto pedagógico, que contempla tanto los discursos educativos, como la historia de la evolución del taller como constructo social. El análisis se estructura sobre los elementos fundantes del acto didáctico: un sujeto que aprende, un sujeto que enseña, un método, la estrategia o procedimiento a través del que se enseña, un contenido y el propio acto docente (Sánchez Cerezo, 1994, 530). Además, se han añadido otros dos elementos que se consideran fundamentales para llevar a cabo el estudio: el contexto de la enseñanza, tanto el tangible como el intangible y la evaluación de la enseñanza y del aprendizaje. El caso de estudio de la presente investigación se sitúa en la Escuela de Arquitectura de Madrid en la actualidad. Sin embargo, no se pretende generar un retrato exacto de esta institución sino utilizarla como ejemplo principal en el desarrollo de los capítulos del método, contenido, acto docente y contexto, en los que también se introducen ejemplos de otras escuelas de arquitectura que amplían los argumentos presentados que constituyen la contextualización teórica del acto pedagógico en los talleres de proyectos arquitectónicos. ABSTRACT Design studio constitutes the core of architectural education. To study its current educational processes involves a theoretical approach of its educational praxis and an historic revision of how its social structure evolved. This structure is inherited from the long tradition of the workshop in which master masons, craftsmen, architects and artists have always been in charge of teaching construction, crafts, architectural design and art. Apprentices were subjected to the authority of their teachers and spent hours practicing, producing and learning along with them. With the establishment of the first Academies of Art and later of Architecture, the interest of the State in artistic and architectural products started growing. The understanding of arts and architecture as a state project entailed the slow, but robust development of a parallel education project. This project coexisted with the masters’ workshops, without the possibility of integration between two, until much later. It was difficult to find a way to synthesize academic “theory” with workshop “practice”. The workshops’ and the Academy's conception about teaching and learning differed significantly. While the Academy represented a verified and explicit knowledge, the workshop worked with a tacit and implicit knowledge. The workshops produced education through artistic practice, while the the Academy organized and verified knowledge. This dual framework has on occasions reached extremes. It is no accident that the biggest known crises in the history of arts education coincide with an increase in the distance between these two "institutions", the workshops and Academies. Furthermore, it seems that most innovative concepts or projects have been founded on restoring the lost balance between the two. In this context, in the field of education, and especially during the 20th century, a debate that contemplated the purpose of education and resulted in two quite differentiated approaches, emerged,. One position claims as the primary purpose of education the development of social awareness and mutuality in individuals. The other approach sets as a purpose developing each student's uniqueness. The quest for the right balance between these two positions is based on the assumption that the general purpose of education is to foster the growth of what is individual in each human being, at the same time harmonizing the individuality thus educed with the organic unity of the social group to which the individual belongs (Read, 2010, 33). This tension forms the basis for many pedagogical discourses, especially the ones utilized in this dissertation. The social structure of architecture studios today demonstrates a very high level of integration between the two institutions, the workshop and the Academy, both in terms of space —where the teaching takes place— as well as on a conceptual and pedagogical level. Architecture studios today have developed a format for teaching and learning that has established a paradigm (Schön, 2008) , not only in architecture, but also in other fields. Under this paradigm, practical and theoretical learning, as well as production and verification of knowledge, complement each other. And although this pedagogical structure presents important variations among different schools of architecture, the principal processes that take place in the studio are sufficiently similar so as to be examined from a common perspective. This research examines the architecture studio from a pedagogical point of view, that takes into account both the educational discourses, as well as the historical evolution of the workshop as a social structure. The analysis presented here is structured on the fundamentals of the teaching act: an individual learning, an individual teaching, a method, strategy or procedure for teaching and learning, the content and the teaching act itself (Sánchez Cerezo, 1994, 530). Two extra elements that were considered essential for carrying out this study have also been added: the context in which teaching takes place, tangible as well as intangible, and the evaluation of teaching and learning. The Madrid School of Architecture in the present day served as a case study. However the aim is not to generate an accurate portrayal of this school but to use it as the principal example for the development of the chapters of method, content, teaching act and context. In addition to that, examples from other schools of architecture are introduced in order to further the presented arguments that constitute the theoretical contextualization of the pedagogical act in architecture studios.

Evaluation of the surface free energy of plant surfaces: toward standardizing the procedure

Plant surfaces have been found to have a major chemical and physical heterogeneity and play a key protecting role against multiple stress factors. During the last decade, there is a raising interest in examining plant surface properties for the development of biomimetic materials. Contact angle measurement of different liquids is a common tool for characterizing synthetic materials, which is just beginning to be applied to plant surfaces. However, some studies performed with polymers and other materials showed that for the same surface, different surface free energy values may be obtained depending on the number and nature of the test liquids analyzed, materials' properties, and surface free energy calculation methods employed. For 3 rough and 3 rather smooth plant materials, we calculated their surface free energy using 2 or 3 test liquids and 3 different calculation methods. Regardless of the degree of surface roughness, the methods based on 2 test liquids often led to the under- or over-estimation of surface free energies as compared to the results derived from the 3-Liquids method. Given the major chemical and structural diversity of plant surfaces, it is concluded that 3 different liquids must be considered for characterizing materials of unknown physico-chemical properties, which may significantly differ in terms of polar and dispersive interactions. Since there are just few surface free energy data of plant surfaces with the aim of standardizing the calculation procedure and interpretation of the results among for instance, different species, organs, or phenological states, we suggest the use of 3 liquids and the mean surface tension values provided in this study.

Haptically assisted connection procedure for the reconstruction of dendritic spines

Dendritic spines are thin protrusions that cover the dendritic surface of numerous neurons in the brain and whose function seems to play a key role in neural circuits. The correct segmentation of those structures is difficult due to their small size and the resulting spines can appear incomplete. This paper presents a four-step procedure for the complete reconstruction of dendritic spines. The haptically driven procedure is intended to work as an image processing stage before the automatic segmentation step giving the final representation of the dendritic spines. The procedure is designed to allow both the navigation and the volume image editing to be carried out using a haptic device. A use case employing our procedure together with a commercial software package for the segmentation stage is illustrated. Finally, the haptic editing is evaluated in two experiments; the first experiment concerns the benefits of the force feedback and the second checks the suitability of the use of a haptic device as input. In both cases, the results shows that the procedure improves the editing accuracy.

A procedure to track vibration modes under changing external factors: application to a pedestrian bridge

A low-cost vibration monitoring system has been developed and installed on an urban steel- plated stress-ribbon footbridge. The system continuously measures: the acceleration (using 18 triaxial MEMS accelerometers distributed along the structure), the ambient temperature and the wind velocity and direction. Automated output-only modal parameter estimation based on the Stochastic Subspace Identification (SSI) is carried out in order to extract the modal parameters, i.e., the natural frequencies, damping ratios and modal shapes. Thus, this paper analyzes the time evolution of the modal parameters over a whole-year data monitoring. Firstly, for similar environmental/operational factors, the uncertainties associated to the time window size used are studied and quantified. Secondly, a methodology to track the vibration modes has been established since several of them with closely-spaced natural frequencies are identified. Thirdly, the modal parameters have been correlated against external factors. It has been shown that this stress-ribbon structure is highly sensitive to temperature variation (frequency changes of more than 20%) with strongly seasonal and daily trends