Aplicaci��n de la metodolog��a ISA al an��lisis de la secuencia de p��rdida del sistema de agua de refrigeraci��n de componentes en una central nuclear con reactor de agua a presi��n

La metodolog��a Integrated Safety Analysis (ISA), desarrollada en el ��rea de Modelaci��n y Simulaci��n (MOSI) del Consejo de Seguridad Nuclear (CSN), es un m��todo de An��lisis Integrado de Seguridad que est�� siendo evaluado y analizado mediante diversas aplicaciones impulsadas por el CSN; el an��lisis integrado de seguridad, combina las t��cnicas evolucionadas de los an��lisis de seguridad al uso: deterministas y probabilistas. Se considera adecuado para sustentar la Regulaci��n Informada por el Riesgo (RIR), actual enfoque dado a la seguridad nuclear y que est�� siendo desarrollado y aplicado en todo el mundo. En este contexto se enmarcan, los proyectos Safety Margin Action Plan (SMAP) y Safety Margin Assessment Application (SM2A), impulsados por el Comit�� para la Seguridad de las Instalaciones Nucleares (CSNI) de la Agencia de la Energ��a Nuclear (NEA) de la Organizaci��n para la Cooperaci��n y el Desarrollo Econ��micos (OCDE) en el desarrollo del enfoque adecuado para el uso de las metodolog��as integradas en la evaluaci��n del cambio en los m��rgenes de seguridad debidos a cambios en las condiciones de las centrales nucleares. El comit�� constituye un foro para el intercambio de informaci��n t��cnica y de colaboraci��n entre las organizaciones miembro, que aportan sus propias ideas en investigaci��n, desarrollo e ingenier��a. La propuesta del CSN es la aplicaci��n de la metodolog��a ISA, especialmente adecuada para el an��lisis seg��n el enfoque desarrollado en el proyecto SMAP que pretende obtener los valores best-estimate con incertidumbre de las variables de seguridad que son comparadas con los l��mites de seguridad, para obtener la frecuencia con la que ��stos l��mites son superados. La ventaja que ofrece la ISA es que permite el an��lisis selectivo y discreto de los rangos de los par��metros inciertos que tienen mayor influencia en la superaci��n de los l��mites de seguridad, o frecuencia de excedencia del l��mite, permitiendo as�� evaluar los cambios producidos por variaciones en el dise��o u operaci��n de la central que ser��an imperceptibles o complicados de cuantificar con otro tipo de metodolog��as. La ISA se engloba dentro de las metodolog��as de APS din��mico discreto que utilizan la generaci��n de ��rboles de sucesos din��micos (DET) y se basa en la Theory of Stimulated Dynamics (TSD), teor��a de fiabilidad din��mica simplificada que permite la cuantificaci��n del riesgo de cada una de las secuencias. Con la ISA se modelan y simulan todas las interacciones relevantes en una central: dise��o, condiciones de operaci��n, mantenimiento, actuaciones de los operadores, eventos estoc��sticos, etc. Por ello requiere la integraci��n de c��digos de: simulaci��n termohidr��ulica y procedimientos de operaci��n; delineaci��n de ��rboles de sucesos; cuantificaci��n de ��rboles de fallos y sucesos; tratamiento de incertidumbres e integraci��n del riesgo. La tesis contiene la aplicaci��n de la metodolog��a ISA al an��lisis integrado del suceso iniciador de la p��rdida del sistema de refrigeraci��n de componentes (CCWS) que genera secuencias de p��rdida de refrigerante del reactor a trav��s de los sellos de las bombas principales del circuito de refrigerante del reactor (SLOCA). Se utiliza para probar el cambio en los m��rgenes, con respecto al l��mite de la m��xima temperatura de pico de vaina (1477 K), que ser��a posible en virtud de un potencial aumento de potencia del 10 % en el reactor de agua a presi��n de la C.N. Zion. El trabajo realizado para la consecuci��n de la tesis, fruto de la colaboraci��n de la Escuela T��cnica Superior de Ingenieros de Minas y Energ��a y la empresa de soluciones tecnol��gicas Ekergy Software S.L. (NFQ Solutions) con el ��rea MOSI del CSN, ha sido la base para la contribuci��n del CSN en el ejercicio SM2A. Este ejercicio ha sido utilizado como evaluaci��n del desarrollo de algunas de las ideas, sugerencias, y los algoritmos detr��s de la metodolog��a ISA. Como resultado se ha obtenido un ligero aumento de la frecuencia de excedencia del da��o (DEF) provocado por el aumento de potencia. Este resultado demuestra la viabilidad de la metodolog��a ISA para obtener medidas de las variaciones en los m��rgenes de seguridad que han sido provocadas por modificaciones en la planta. Tambi��n se ha mostrado que es especialmente adecuada en escenarios donde los eventos estoc��sticos o las actuaciones de recuperaci��n o mitigaci��n de los operadores pueden tener un papel relevante en el riesgo. Los resultados obtenidos no tienen validez m��s all�� de la de mostrar la viabilidad de la metodolog��a ISA. La central nuclear en la que se aplica el estudio est�� clausurada y la informaci��n relativa a sus an��lisis de seguridad es deficiente, por lo que han sido necesarias asunciones sin comprobaci��n o aproximaciones basadas en estudios gen��ricos o de otras plantas. Se han establecido tres fases en el proceso de an��lisis: primero, obtenci��n del ��rbol de sucesos din��mico de referencia; segundo, an��lisis de incertidumbres y obtenci��n de los dominios de da��o; y tercero, cuantificaci��n del riesgo. Se han mostrado diversas aplicaciones de la metodolog��a y ventajas que presenta frente al APS cl��sico. Tambi��n se ha contribuido al desarrollo del prototipo de herramienta para la aplicaci��n de la metodolog��a ISA (SCAIS). ABSTRACT The Integrated Safety Analysis methodology (ISA), developed by the Consejo de Seguridad Nuclear (CSN), is being assessed in various applications encouraged by CSN. An Integrated Safety Analysis merges the evolved techniques of the usually applied safety analysis methodologies; deterministic and probabilistic. It is considered as a suitable tool for assessing risk in a Risk Informed Regulation framework, the approach under development that is being adopted on Nuclear Safety around the world. In this policy framework, the projects Safety Margin Action Plan (SMAP) and Safety Margin Assessment Application (SM2A), set up by the Committee on the Safety of Nuclear Installations (CSNI) of the Nuclear Energy Agency within the Organization for Economic Co-operation and Development (OECD), were aimed to obtain a methodology and its application for the integration of risk and safety margins in the assessment of the changes to the overall safety as a result of changes in the nuclear plant condition. The committee provides a forum for the exchange of technical information and cooperation among member organizations which contribute their respective approaches in research, development and engineering. The ISA methodology, proposed by CSN, specially fits with the SMAP approach that aims at obtaining Best Estimate Plus Uncertainty values of the safety variables to be compared with the safety limits. This makes it possible to obtain the exceedance frequencies of the safety limit. The ISA has the advantage over other methods of allowing the specific and discrete evaluation of the most influential uncertain parameters in the limit exceedance frequency. In this way the changes due to design or operation variation, imperceptibles or complicated to by quantified by other methods, are correctly evaluated. The ISA methodology is one of the discrete methodologies of the Dynamic PSA framework that uses the generation of dynamic event trees (DET). It is based on the Theory of Stimulated Dynamics (TSD), a simplified version of the theory of Probabilistic Dynamics that allows the risk quantification. The ISA models and simulates all the important interactions in a Nuclear Power Plant; design, operating conditions, maintenance, human actuations, stochastic events, etc. In order to that, it requires the integration of codes to obtain: Thermohydraulic and human actuations; Even trees delineation; Fault Trees and Event Trees quantification; Uncertainty analysis and risk assessment. This written dissertation narrates the application of the ISA methodology to the initiating event of the Loss of the Component Cooling System (CCWS) generating sequences of loss of reactor coolant through the seals of the reactor coolant pump (SLOCA). It is used to test the change in margins with respect to the maximum clad temperature limit (1477 K) that would be possible under a potential 10 % power up-rate effected in the pressurized water reactor of Zion NPP. The work done to achieve the thesis, fruit of the collaborative agreement of the School of Mining and Energy Engineering and the company of technological solutions Ekergy Software S.L. (NFQ Solutions) with de specialized modeling and simulation branch of the CSN, has been the basis for the contribution of the CSN in the exercise SM2A. This exercise has been used as an assessment of the development of some of the ideas, suggestions, and algorithms behind the ISA methodology. It has been obtained a slight increase in the Damage Exceedance Frequency (DEF) caused by the power up-rate. This result shows that ISA methodology allows quantifying the safety margin change when design modifications are performed in a NPP and is specially suitable for scenarios where stochastic events or human responses have an important role to prevent or mitigate the accidental consequences and the total risk. The results do not have any validity out of showing the viability of the methodology ISA. Zion NPP was retired and information of its safety analysis is scarce, so assumptions without verification or approximations based on generic studies have been required. Three phases are established in the analysis process: first, obtaining the reference dynamic event tree; second, uncertainty analysis and obtaining the damage domains; third, risk quantification. There have been shown various applications of the methodology and advantages over the classical PSA. It has also contributed to the development of the prototype tool for the implementation of the ISA methodology (SCAIS).

Teor��a y pr��ctica de la restauraci��n de la Mezquita-Catedral de C��rdoba durante el siglo XX

La Mezquita-Catedral de C��rdoba es un edificio vivo. Un edificio que ha sido transformado sucesivamente por hombres de razas, culturas y religiones distintas durante sus m��s de 1.200 a��os de vida y que, a pesar de ello, no ha dejado de estar en uso ni uno solo de esos d��as de esa larga vida. De esta forma, el edificio se muestra ante el visitante como un complejo objeto arquitect��nico, resultado de una continua transformaci��n. La capacidad de la transformaci��n de los edificios es algo inherente a su propia condici��n arquitect��nica, no es un hecho exclusivo de la Mezquita-Catedral. Sin embargo, en este edificio esa transformaci��n se produce con una gran intensidad y sin p��rdida de su autenticidad. Tradicionalmente, los edificios se han adaptado a los nuevos requerimientos de cada ��poca en un proceso que ha buscado en el propio edificio las leyes o principios que hab��an de regir la intervenci��n. De esta forma, tanto las sucesivas ampliaciones de la Mezquita de Abd al-Rahman I como las siguientes intervenciones cristianas debieron asumir lo preexistente como material de trabajo. As��, los arquitectos del califa al-Hakam II dialogaron con sus antecesores complejizando el espacio que recibieron, as�� como los Hern��n Ruiz consiguieron un nuevo organismo resultante de la introducci��n de su arquitectura luminosa en la trama hispanomusulmana. El siglo XIX confirm�� el deseo por descubrir las huellas de un pasado esplendoroso que la intervenci��n barroca hab��a silenciado bajo un tratamiento homog��neo del espacio. La recuperaci��n de esas huellas supuso, hace exactamente dos siglos, el inicio de la ��ltima gran etapa en la transformaci��n del edificio, la de la restauraci��n. La f��brica es considerada como objeto a conservar y los esfuerzos desde ese momento se centraron en la recuperaci��n de la arquitectura omeya latente. De este modo, la pr��ctica de la restauraci��n como disciplina se encontr�� absolutamente influenciada por la Arqueolog��a como ��nica fuente de conocimiento. Las intervenciones buscaban lo original como modo de recuperar espacial y formalmente aquel pasado, concentr��ndose en los lugares del edificio considerados como esenciales. La declaraci��n del edificio como monumento nacional en 1882 propici�� que el Estado se hiciera cargo de su mantenimiento y conservaci��n, sustituyendo en esa tarea a los Obispos y Cabildos del siglo XIX, que tuvieron un entendimiento muy avanzado para su ��poca. La llegada del arquitecto Vel��zquez Bosco en las ��ltimas d��cadas del siglo XIX supuso un cambio trascendental en la historia del edificio, puesto que recibi�� un edificio con importantes deterioros y consigui�� poner las bases del edificio que hoy contemplamos. El empe��o por la recuperaci��n material y espacial devolvi�� a la Mezquita-Catedral buena parte de su imagen original, reproduciendo con exactitud los modelos hallados en las exploraciones arqueol��gicas. La llegada de Antonio Fl��rez tras la muerte de Vel��zquez Bosco supuso la traslaci��n al edificio del debate disciplinar que se desarroll�� en las dos primeras d��cadas del siglo XX. Fl��rez procur�� un nuevo entendimiento de la intervenci��n, considerando la conservaci��n como actuaci��n prioritaria. En 1926 el Estado reform�� la manera en que se atend��a al patrimonio con la creaci��n de un sistema de zonas y unos arquitectos a cargo de ellas. La existencia de un nuevo marco legislativo apuntal�� esa nueva visi��n conservativa, avalada por la Carta de Atenas de 1931. Este modelo restauraci��n cient��fica hu��a de la intervenci��n en estilo y valoraba la necesidad de intervenir de la manera m��s escueta posible y con un lenguaje diferenciado, bas��ndose en los datos que ofrec��a la Arqueolog��a. Por tanto, se continuaba con la valoraci��n del edificio como documento hist��rico, buscando en este caso una imagen diferenciada de la intervenci��n frente a la actitud mim��tica de Vel��zquez. Resulta destacable la manera en la que el historiador Manuel G��mez-Moreno influy�� en varias generaciones de arquitectos, arque��logos e historiadores, tanto en el entendimiento cient��fico de la restauraci��n como en la propia estructura administrativa. La labor desarrollada en el edificio por Jos�� M�� Rodr��guez Cano primero y F��lix Hern��ndez a continuaci��n estuvo influida de manera te��rica por el m��todo de G��mez-Moreno, aunque en muchos aspectos su labor no represent�� una gran diferencia con lo hecho por Vel��zquez Bosco. La b��squeda de lo original volvi�� a ser recurrente, pero la carga econ��mica del mantenimiento de un edificio tan extenso conllev�� la no realizaci��n de muchos de los proyectos m��s ambiciosos. Esta obsesiva b��squeda de la imagen original del edificio tuvo su ��ltima y anacr��nica etapa con la intervenci��n de la Direcci��n General de Arquitectura en los 70. Sin embargo, el agotamiento del modelo cient��fico ya hab��a propiciado un nuevo escenario a nivel europeo, que cristaliz�� en la Carta de Venecia de 1964 y en una nueva definici��n del objeto a preservar, m��s all�� del valor como documento hist��rico. Esta nueva posici��n te��rica tuvo su traslaci��n al modelo restaurador espa��ol en el ��ltimo cuarto de siglo XX, coincidiendo con la Transici��n. El arquitecto Dionisio Hern��ndez Gil defendi�� una interpretaci��n distinta a la de los arque��logos y de los historiadores, que hab��a prevalecido durante todo el siglo. En opini��n de Hern��ndez Gil, los problemas de intervenci��n deb��an enfocarse fundamentalmente como problemas de Arquitectura, abandonando la idea de que solamente pod��an ser resueltos por especialistas. Esta convicci��n te��rica fue defendida desde la nueva Administraci��n y depar�� la utilizaci��n de unos criterios de intervenci��n particularizados, provenientes del an��lisis multifocal de cada situaci��n y no s��lo desde el valor de los edificios como documentos hist��ricos. Y este cambio tuvo su traslaci��n a la Mezquita-Catedral con la pr��ctica de Gabriel Ruiz Cabrero y Gabriel Rebollo. En consecuencia con esa nueva perspectiva, aceptaron el edificio que recibieron, sustituyendo la b��squeda de aquella p��gina original por la aceptaci��n de cada una de las p��ginas de su historia y el respeto a las t��cnicas constructivas del pasado. La b��squeda de soluciones espec��ficas desde el propio objeto arquitect��nico signific�� la renovada atenci��n a la potente estructura formal-constructiva como origen de toda reflexi��n. Considerar la Mezquita-Catedral en primer lugar como Arquitectura implicaba la atenci��n a todo tipo de factores adem��s de los hist��ricos, como medio para preservar su autenticidad. Esta tesis pretende demostrar que la pr��ctica de la restauraci��n realizada en la Mezquita-Catedral a lo largo del siglo XX ha evolucionado desde la b��squeda de lo original hasta la b��squeda de lo aut��ntico, como reflejo de una visi��n basada en lo arqueol��gico frente a una renovada visi��n arquitect��nica m��s completa, que incluye a la anterior. La consideraci��n de la intervenci��n en este edificio como otra p��gina m��s de su historia y no como la ��ltima, significa la reedici��n de un mecanismo recurrente en la vida del edificio y un nuevo impulso en ese proceso de continua transformaci��n. ABSTRACT The Mosque-Cathedral of Cordoba is a living building. A building transformed by men of different races, cultures and religions during more than 1.200 years old and that, nevertheless, it has continued to be in use all days in that long life. Thus, the building shows to the visitor as a complex architectural object, the result of continuous transformation. This transformation capacity of the buildings is inherent in their own architectural condition, it���s not an exclusive fact of the Mosque-Cathedral. However, in this building that transformation happens with a great intensity, without losing their authenticity. Traditionally, buildings have been adapted to the new requirements of times in a process that looked for laws or principles in order to guide the intervention. Thus, both the successive enlargements of the Mosque of Abd al-Rahman and Christian interventions must assume the preexistence as a working material. So, the architects of the caliph al-Hakam II spoke to their predecessors, complexing the receiving space, as well as Hernan Ruiz got a new organism as result the introduction of his luminous architecture into hispanic-muslim weft. The nineteenth century confirmed the desire to discover the traces of a glorious past that Baroque intervention had silenced, under a uniform space treatment. Exactly two centuries ago, the recovery of these traces meant the start of the last major phase in the transformation of the building: the restoration. The building was considered subject to conserve and since then, efforts focused on the recovery of latent Umayyad architecture. Thus, the practice of restoration as a discipline was absolutely influenced by Archaeology as the only source of knowledge. Interventions were seeking the original as the way to recover that past in a space and formal way, concentrating on essential sites of the building. The statement as a national monument in 1882 prompted the State take charge of its maintenance and preservation, replacing to the nineteenth century Bishops and Cabildos, which had a very advanced understanding for that time. The arrival of the architect Velazquez Bosco in the last decades of the nineteenth century involved a momentous change in the history of the building, since he received a building with significant damage and he achieved the foundations of the building that we can see today. Efforts to a material and space recover returned the Mosque-Cathedral to its original image, accurately reproducing the models found in archaeological explorations. The arrival of Antonio Florez after Velazquez���s death involved the translation of discipline debate, which was developed in the first two decades of the twentieth century. Florez tried a new understanding of the intervention, considering conservation as a priority action. In 1926, the State reformed the way in which heritage was attended, creating a zones system with a few architects in charge of them. The existence of a new legislative framework, underpinned this new conservative vision, supported by the Athens Charter of 1931. This scientific restoration model fleeing from intervention in style and it appreciated the need to intervene in the most concise way, with a distinct language based on the data offered by Archaeology. Therefore, it continued with the appraisement of the building as a historical document, seeking in this case a differentiated image of intervention, against Velazquez mimetic attitude. It is remarkable the way in which the historian Manuel Gomez-Moreno influenced several generations of architects, archaeologists and historians, both in the scientific understanding of the restoration and the administrative structure. The work of Jose Maria Rodriguez Cano first and then Felix Hernandez was theoretically influenced by the Gomez-Moreno���s method, although in many respects their work did not represent a great difference to Velazquez Bosco. The search of the original returned to recur, but the economic charge of maintaining such a large building led to the non-realization of many of the most ambitious projects. This obsessive search for the original image of the building had its last and anachronistic stage with the intervention of the Department of Architecture at 70���s. However, the exhaustion of the scientific model had already led to a new scenario at European level, which crystallized in the Venice Charter of 1964 and a new definition of the object to be preserved beyond the value as a historical document. This new theoretical position had its translation to Spanish restaurateur model in the last quarter of the twentieth century, coinciding with the Transition. The architect Dionisio Hernandez Gil defended a different interpretation from archaeologists and historians, that had prevailed throughout the century. According to Hernandez Gil, the problems of intervention should focus primarily as architectural issues, abandoning the idea that they could only be determined by specialist. This theoretical conviction was defended from the new administration and led to the use of particularized criteria, from a multifocal analysis of each situation. And this change had its translation to the Mosque with the practice of Gabriel Ruiz Cabrero and Gabriel Rebollo. Consistent with this new perspective, they accepted the receiving building, replacing the search on original page for acceptance of all historical pages and respecting the constructive techniques of the past. The search for specific solutions from the architectural object meant the renewed attention to the powerful formal-constructive structure as the origin of all thought. Consider the Mosque-Cathedral as Architecture, involved the attention to all kinds of factors in addition to the historical, as a means to preserve its authenticity. This thesis aims to demonstrate that the practice of restoration in the Mosque-Cathedral throughout the twentieth century has evolved from the search of the original to the search for the authentic, reflecting a vision based on the archaeological against a renewed more complete architectural vision, including the above. Consideration of intervention in this building as another page in its history and not the last one, means the reissue of an own mechanism and a new impetus in that continuous transformation process.

Design of a generalized tool for the performance assessment under sail based on analytical, numerical and empirical results : a global sailing yacht meta-model

La evaluaci��n de las prestaciones de las embarcaciones a vela ha constituido un objetivo para ingenieros navales y marinos desde los principios de la historia de la navegaci��n. El conocimiento acerca de estas prestaciones, ha crecido desde la identificaci��n de los factores clave relacionados con ellas(eslora, estabilidad, desplazamiento y superficie v��lica), a una comprensi��n m��s completa de las complejas fuerzas y acoplamientos involucrados en el equilibrio. Junto con este conocimiento, la aparici��n de los ordenadores ha hecho posible llevar a cabo estas tareas de una forma sistem��tica. Esto incluye el c��lculo detallado de fuerzas, pero tambi��n, el uso de estas fuerzas junto con la descripci��n de una embarcaci��n a vela para la predicci��n de su comportamiento y, finalmente, sus prestaciones. Esta investigaci��n tiene como objetivo proporcionar una definici��n global y abierta de un conjunto de modelos y reglas para describir y analizar este comportamiento. Esto se lleva a cabo sin aplicar restricciones en cuanto al tipo de barco o c��lculo, sino de una forma generalizada, de modo que sea posible resolver cualquier situaci��n, tanto estacionaria como en el dominio del tiempo. Para ello se comienza con una definici��n b��sica de los factores que condicionan el comportamiento de una embarcaci��n a vela. A continuaci��n se proporciona una metodolog��a para gestionar el uso de datos de diferentes or��genes para el c��lculo de fuerzas, siempre con el la soluci��n del problema como objetivo. Esta ��ltima parte se plasma en un programa de ordenador, PASim, cuyo prop��sito es evaluar las prestaciones de diferentes ti pos de embarcaciones a vela en un amplio rango de condiciones. Varios ejemplos presentan diferentes usos de PASim con el objetivo de ilustrar algunos de los aspectos discutidos a lo largo de la definici��n del problema y su soluci��n . Finalmente, se presenta una estructura global de cara a proporcionar una representaci��n virtual de la embarcaci��n real, en la cual, no solo e l comportamiento sino tambi��n su manejo, son cercanos a la experiencia de los navegantes en el mundo real. Esta estructura global se propone como el n��cleo (un motor de software) de un simulador f��sico para el que se proporciona una especificaci��n b��sica. ABSTRACT The assessment of the performance of sailing yachts, and ships in general, has been an objective for naval architects and sailors since the beginning of the history of navigation. The knowledge has grown from identifying the key factors that influence performance(length, stability, displacement and sail area), to a much more complete understanding of the complex forces and couplings involved in the equilibrium. Along with this knowledge, the advent of computers has made it possible to perform the associated tasks in a systematic way. This includes the detailed calculation of forces, but also the use of those forces, along with the description of a sailing yacht, to predict its behavior, and ultimately, its performance. The aim of this investigation is to provide a global and open definition of a set of models and rules to describe and analyze the behavior of a sailing yacht. This is done without applying any restriction to the type of yacht or calculation, but rather in a generalized way, capable of solving any possible situation, whether it is in a steady state or in the time domain. First, the basic definition of the factors that condition the behavior of a sailing yacht is given. Then, a methodology is provided to assist with the use of data from different origins for the calculation of forces, always aiming towards the solution of the problem. This last part is implemented as a computational tool, PASim, intended to assess the performance of different types of sailing yachts in a wide range of conditions. Several examples then present different uses of PASim, as a way to illustrate some of the aspects discussed throughout the definition of the problem and its solution. Finally, a global structure is presented to provide a general virtual representation of the real yacht, in which not only the behavior, but also its handling is close to the experience of the sailors in the real world. This global structure is proposed as the core (a software engine) of a physical yacht simulator, for which a basic specification is provided.

Systematic Process for Building a Fault Diagnoser Based on Petri Nets Applied to a Helicopter

This work presents a systematic process for building a Fault Diagnoser (FD), based on Petri Nets (PNs) which has been applied to a small helicopter. This novel tool is able to detect both intermittent and permanent faults. The work carried out is discussed from theoretical and practical point of view. The procedure begins with a division of the whole system into subsystems, which are the devices that have to be modeled by using PN, considering both the normal and fault operations. Subsequently, the models are integrated into a global Petri Net diagnoser (PND) that is able to monitor a whole helicopter and show critical variables to the operator in order to determine the UAV health, preventing accidents in this manner. A Data Acquisition System (DAQ) has been designed for collecting data during the flights and feeding PN diagnoser with them. Several real flights (nominal or under failure) have been carried out to perform the diagnoser setup and verify its performance. A summary of the validation results obtained during real flight tests is also included. An extensive use of this tool will improve preventive maintenance protocols for UAVs (especially helicopters) and allow establishing recommendations in regulations

Virus-encoded suppressor of posttranscriptional gene silencing targets a maintenance step in the silencing pathway

Certain plant viruses encode suppressors of posttranscriptional gene silencing (PTGS), an adaptive antiviral defense response that limits virus replication and spread. The tobacco etch potyvirus protein, helper component-proteinase (HC-Pro), suppresses PTGS of silenced transgenes. The effect of HC-Pro on different steps of the silencing pathway was analyzed by using both transient Agrobacterium tumefaciens-based delivery and transgenic systems. HC-Pro inactivated PTGS in plants containing a preexisting silenced ��-glucuronidase (GUS) transgene. PTGS in this system was associated with both small RNA molecules (21���26 nt) corresponding to the 3��� proximal region of the transcribed GUS sequence and cytosine methylation of specific sites near the 3��� end of the GUS transgene. Introduction of HC-Pro into these plants resulted in loss of PTGS, loss of small RNAs, and partial loss of methylation. These results suggest that HC-Pro targets a PTGS maintenance (as opposed to an initiation or signaling) component at a point that affects accumulation of small RNAs and methylation of genomic DNA.

Maintenance of pre-mRNA secondary structure by epistatic selection.

Linkage disequilibrium between polymorphisms in a natural population may result from various evolutionary forces, including random genetic drift due to sampling of gametes during reproduction, restricted migration between subpopulations in a subdivided population, or epistatic selection. In this report, we present evidence that the majority of significant linkage disequilibria observed in introns of the alcohol dehydrogenase locus (Adh) of Drosophila pseudoobscura are due to epistatic selection maintaining secondary structure of precursor mRNA (pre-mRNA). Based on phylogenetic-comparative analysis and a likelihood approach, we propose secondary structure models of Adh pre-mRNA for the regions of the adult intron and intron 2 where clustering of linkage disequilibria has been observed. Furthermore, we applied the likelihood ratio test to the phylogenetically predicted secondary structure in intron 1. In contrast to the other two structures, polymorphisms associated with the more conserved stem-loop structure of intron 1 are in low frequency, and linkage disequilibria have not been observed. These findings are qualitatively consistent with a model of compensatory fitness interactions. This model assumes that mutations disrupting pairing in a secondary structural element are individually deleterious if they destabilize a functionally important structure; a second "compensatory" mutation, however, may restabilize the structure and restore fitness.

Aprendizagem de substantivos e adjetivos por meio de leitura compartilhada para crian��as com desenvolvimento t��pico e com S��ndrome de Down

A leitura compartilhada de livros para crian��as �� uma atividade que tem sido estudada como forma de ensino incidental de vocabul��rio, que envolve, dentre outros processos, o responder por exclus��o. O objetivo do presente trabalho foi investigar a ocorr��ncia de aprendizagem de rela����es entre est��mulos visuais (figuras) com seus respectivos est��mulos auditivos (palavras) a partir de diferentes condi����es de leitura compartilhada de livros para crian��as com S��ndrome de Down (SD) e com desenvolvimento t��pico (DT). Para a pesquisa foram desenvolvidos dois estudos. No Estudo 1, participaram seis crian��as com SD com seis a sete anos, e seis crian��as com DT com tr��s a quatro anos (amostras pareadas em fun����o do n��vel de vocabul��rio). Foi utilizado um livro de hist��ria produzido pela pesquisadora, no qual havia dois substantivos e dois adjetivos desconhecidos (est��mulos visuais S1, S2, A1, A2), apresentados uma ��nica vez na hist��ria. Esse livro foi lido para cada crian��a duas vezes em sequ��ncia por sess��o e em cada sess��o foi realizada uma condi����o de leitura diferente. Foram apresentadas tr��s condi����es de leitura e cada crian��a passou por todas, mas em diferentes ordens (contrabalanceamento). Na Condi����o 1, o livro foi lido para a crian��a sem interven����es. Na Condi����o 2, o livro foi lido para a crian��a e ela tinha que repetir o nome dos est��mulos desconhecidos. Na Condi����o 3, o livro foi lido e foram realizadas perguntas relacionadas aos est��mulos-alvo. Ao final de cada sess��o foram realizadas sondas de aprendizagem (sondas de emparelhamento ao modelo e nomea����o), e ap��s uma semana da ��ltima sess��o foi aplicada uma sonda de manuten����o e uma de generaliza����o. As crian��as com DT apresentaram maior n��mero de acertos que as com SD, e os acertos foram mais relacionados ao est��mulo S1. As crian��as n��o aprenderam a rela����o nome-cor. A an��lise dos resultados sugeriu que o n��mero de est��mulos-alvo era excessivo e com apresenta����es insuficientes no livro. No Estudo 2 participaram seis crian��as com DT de 3 a 4 anos e seis crian��as com SD, de 5 a 8 anos. O procedimento utilizado no Estudo 2 foi semelhante ao primeiro com as seguintes altera����es no livro: utiliza����o de apenas duas rela����es-alvo (um substantivo-alvo e um adjetivo-alvo - S2 e A3), cada uma sendo apresentada tr��s vezes ao longo da hist��ria, em figuras que possibilitavam o responder por exclus��o. Tamb��m foi acrescentada uma tentativa de exclus��o nas sondas de aprendizagem. Nesse estudo, todas as crian��as com DT conseguiram selecionar e nomear est��mulo S2 e duas mostraram ind��cios de aprendizagem do est��mulo A3. As crian��as com SD apresentaram um menor n��mero de acertos nas sondas de emparelhamento, mas apresentaram algumas nomea����es corretas, o que n��o foi observado no Estudo 1. Os dados sugerem que as mudan��as realizadas no livro melhoram o desempenho das crian��as com DT, mas n��o o das crian��as com SD. N��o foram encontradas diferen��as entre as condi����es de leituras nos dois estudos. No entanto, s��o necess��rios estudos adicionais para avaliar essas diferentes condi����es e as vari��veis envolvidas na aprendizagem de palavras a partir da leitura compartilhada de livro.

Ensaio cl��nico randomizado do uso do curativo gel de clorexidina para a preven����o da coloniza����o do cateter venoso central em pacientes adultos cr��ticos

Os acessos venosos s��o indispens��veis para assist��ncia do paciente em situa����o cr��tica. O cateter venoso central (CVC) �� um acesso que viabiliza a terap��utica dessa clientela, mas o seu uso pode levar �� infec����es. Estas infec����es ocasionam maior perman��ncia hospitalar, elevam os custos totais das institui����es e aumentam a morbidade e a mortalidade do paciente. O uso de curativos como cobertura do s��tio de sa��da do CVC �� eficaz na preven����o das infec����es relacionadas a estes cateteres, em particular, o uso de curativos impregnados com antiss��pticos como o curativo gel de clorexidina. Este estudo teve como objetivo comparar a efetividade do curativo gel de clorexidina com a do filme transparente de poliuretano na preven����o da coloniza����o do cateter venoso central em pacientes adultos cr��ticos. Trata-se de estudo experimental, do tipo ensaio cl��nico randomizado, com tratamentos em paralelo, prospectivo e monoc��ntrico, realizado de acordo com as recomenda����es do Consolidated Standards of Reporting Trials (CONSORT). O estudo foi realizado na Unidade de Terapia Intensiva e na Unidade Coronariana de um hospital de ensino do interior do Estado de S��o Paulo. Participaram do estudo 102 indiv��duos hospitalizados nestes locais, divididos aleatoriamente em dois grupos: grupo interven����o, no qual o tipo de cobertura utilizada foi o curativo de gel de clorexidina e grupo controle, que utilizou como cobertura o filme transparente de poliuretano. O desfecho prim��rio mensurado foi a coloniza����o do cateter e os desfechos secund��rios foram a infec����o cl��nica do s��tio de sa��da, a infec����o microbiol��gica do s��tio de sa��da e a infec����o da corrente sangu��nea relacionada ao cateter. Para a coleta de dados foi elaborado um instrumento, e este validado quanto ao seu conte��do e forma por 13 enfermeiros pertencentes aos locais do estudo. Estes profissionais foram treinados para a realiza����o dos curativos e coleta das pontas dos cateteres centrais, swabs dos s��tios de sa��da e hemoculturas. An��lises descritivas foram usadas para todas as vari��veis do estudo. O teste Exato de Fisher foi utilizado para comparar as propor����es de cada desfecho nos grupos de interven����o e controle, e a regress��o log��stica para explorar se a coloniza����o no CVC poderia ser associada com o tempo de uso do cateter e com o Acute Physiology and Chronic Health Evaluation II (APACHE II) dos pacientes do estudo. De acordo com os resultados n��o houve diferen��a estatisticamente significante entre a coloniza����o nos dois grupos (p valor = 1.00), para a infec����o microbiol��gica do s��tio de sa��da (p valor = 0.08), para a infec����o cl��nica do s��tio de sa��da (p valor = 0.77) e para as infec����es da corrente sangu��nea relacionadas ao cateter (p valor = 1,00). Conclui-se que o presente estudo pode contribuir para que as unidades de sa��de tenham subs��dios para realizar a escolha do tipo de curativo baseado em suas necessidades institucionais e no desenvolvimento de protocolos relacionados �� medidas de inser����o e manuten����o do cateter, bem como medidas educativas permanentes

Caracteriza����o do potencial evocado auditivo cortical P1-N1-P2 em crian��as com estimula����o bimodal

Introdu����o: O implante coclear (IC) amplamente aceito como forma de interven����o e (re) habilita����o nas perdas auditivas severas e profundas nas diversas faixas et��rias. Contudo observa-se no usu��rio do IC unilateral queixas como localiza����o e compreens��o sonora em meio ao ru��do, gerado pelo padr��o anormal de estimula����o sensorial. A fim de fornecer os benef��cios da audi����o binaural, �� preconizado a estimula����o bilateral, seja por meio do IC bilateral ou com a adapta����o de um aparelho de amplifica����o sonora individual (AASI) contralateralmente ao IC. Esta ��ltima condi����o �� referida como estimula����o bimodal, quando temos, concomitantemente dois modos de estimula����o: El��trica (IC) e ac��stica (AASI). N��o h�� dados suficientes na literatura voltados �� popula����o infantil que esclare��a ou demonstre o desenvolvimento do c��rtex auditivo na audi����o bimodal. Ressalta-se que n��o foram encontrados estudos em crian��as. Objetivo: Caracterizar o PEAC complexo P1, N1 P2 em usu��rios da estimula����o bimodal e verificar se h�� correla����o com testes de percep����o de fala. Metodologia: Estudo descritivo de s��ries de casos, com a realiza����o do PEAC em cinco crian��as usu��rias da estimula����o bimodal, a partir da metodologia proposta por Ventura (2008) utilizando o sistema Smart EP USB Jr da Intelligent Hearing Systems. Foi utilizado o som de fala /da/, apresentado em campo livre. O exame ser�� realizado em tr��s situa����es: Somente IC, IC e AASI e somente AASI. A an��lise dos dados dos potenciais corticais foi realizada ap��s a marca����o da presen��a ou aus��ncia dos componentes do complexo P1-N1-P2 por dois ju��zes com experi��ncia em potenciais evocados. Resultados: Foi obtida a capta����o do PEAC em todas as crian��as em todas as situa����es de teste, al��m do que foi poss��vel observar a correla����o destes com os testes de percep����o auditiva da fala. Foi poss��vel verificar que o registro dos PEAC �� um procedimento vi��vel para a avalia����o da crian��a com estimula����o bimodal, por��m, ainda n��o h�� dados suficientes quanto a utiliza����o deste para a avalia����o e indica����o do IC bilateral.

Seismic behavior of a masonry chimney with severe cracking condition: preliminary study

This paper presents a structural analysis of a masonry chimney built in the 1940s, which is currently being cataloged as local interest heritage. This structure has not served any industrial purpose for the last thirty years. The chimney is located in the town of Agost (Alicante - Spain) and directly exposed to the prevailing winds from the sea, as it is approximately 12 km away from the waterfront and there are not any significant barriers, which could protect the structure against the wind. There are longitudinal cracks and fissures all along the shaft because of the chimney���s geometrical characteristics, the effect of the masonry creep and especially the lack of maintenance. Moreover, there is also a permanent bending deformation in the upper 1/3 of the height due to the wind pressure. A numerical analysis for the static behavior against gravity and wind loads was performed using the structure���s current conditions after a detailed report of its geometry, its construction system and the cracking pattern. Afterwards, the dynamic behavior was studied, i.e. a seismic analysis using both response spectra and accelerograms in order to examine the structural stability. This work shows the pre-monitoring analysis before any experimental testing. Using the current results the future test conditions will be determined (e.g. number of sensors and monitoring point location, excitation systems, etc) prior to a possible structural reinforcement by applying composite material (fiber reinforced polymers).

Is a cluster a necessary condition for success? The case of Benidorm

This paper analyses the application of the cluster concept to tourist destinations using Benidorm as a case study. A questionnaire was administered to tourism firms based in Benidorm in order to determine whether this destination currently constitutes a tourism cluster or whether it possesses the ideal characteristics to become a cluster with the private agents' collaboration, that is, whether it is a potential cluster. The results obtained from this research indicate that Benidorm's success is not derived from the presence of a cluster due to a series of elements that prevent its existence. In this destination there is a need to strengthen cooperation between public and private agents (especially in those areas that determine the competitive advantage of the destination) and to design a strategy based on shared goals. Both of these elements are fundamental for the characterisation of a cluster.

Moderators of two Indicated Cognitive-Behavioral Depression Prevention Approaches for Adolescents in a School-Based Effectiveness Trial

Objective: Our aim was to identify moderators of the effects of a cognitive behavioral group-based prevention program (CB group) and CB bibliotherapy, relative to an educational brochure control condition and to one another, in a school-based effectiveness randomized controlled prevention trial. Method: 378 adolescents (M age �� 15.5, 68% female) with elevated depressive symptoms were randomized in one of three conditions and were assessed at pretest, posttest, and 6-month follow-up. We tested the moderating effect of three individual (baseline depressive symptoms, negative attributional style, substance use), three environmental (negative life events, parental support, peer support), and two sociodemographic (sex, age) characteristics. Results: Baseline depressive symptoms interacted with condition and time. Decomposition indicated that elevated baseline depressive symptoms amplified the effect of CB bibliotherapy at posttest (but not 6-month follow-up) relative to the control condition, but did not modify the effect of CB group relative to the control condition or relative to bibliotherapy. Specifically, CB bibliotherapy resulted in lower posttest depressive symptoms than the control condition in individuals with elevated, but not average or low baseline symptoms. We found no interaction effect for other putative moderators. Conclusions: Our findings suggest that bibliotherapy is effective only in participants who have elevated depressive symptoms at baseline. The fact that no study variable moderated the effects of CB group, which had a significant main effect in reducing depressive symptoms relative to the control condition, suggests that this indicated prevention intervention is effective for a wide range of adolescents.

Group-Based Symptom Trajectories in Indicated Prevention of Adolescent Depression

Background: Adolescent depression prevention research has focused on mean intervention outcomes, but has not considered heterogeneity in symptom course. Here, we empirically identify subgroups with distinct trajectories of depressive symptom change among adolescents enrolled in two indicated depression preven- tion trials and examine how cognitive-behavioral (CB) interventions and baseline predictors relate to trajectory membership. Methods: Six hundred thirty-one participants were assigned to one of three conditions: CB group intervention, CB bibliotherapy, and brochure control. We used group-based trajectory modeling to identify trajectories of depressive symptoms from pretest to 2-year follow-up. We examined associations between class membership and conditions using chi- square tests and baseline predictors using multinomial regressions. Results: We identi���ed four trajectories in the full sample. Qualitatively similar trajectories were found in each condition separately. Two trajectories of positive symptom course (low-declining, high-declining) had declining symptoms and were dis- tinguished by baseline symptom severity. Two trajectories of negative course (high-persistent, resurging), respectively, showed no decline in symptoms or de- cline followed by symptom reappearance. Participants in the brochure control condition were signi���cantly more likely to populate the high-persistent trajectory relative to either CB condition and were signi���cantly less likely to populate the low-declining trajectory relative to CB group. Several baseline factors predicted trajectory classes, but gender was the most informative prognostic factor, with males having increased odds of membership in a high-persistent trajectory rel- ative to other trajectories. Conclusions: Findings suggest that CB preventive interventions do not alter the nature of trajectories, but reduce the risk that adolescents follow a trajectory of chronically elevated symptoms.

Moderators of two Indicated Cognitive-Behavioral Depression Prevention Approaches for Adolescents in a School-Based Effectiveness Trial

Objective: Our aim was to identify moderators of the effects of a cognitive behavioral group-based prevention program (CB group) and CB bibliotherapy, relative to an educational brochure control condition and to one another, in a school-based effectiveness randomized controlled prevention trial. Method: 378 adolescents (M age �� 15.5, 68% female) with elevated depressive symptoms were randomized in one of three conditions and were assessed at pretest, posttest, and 6-month follow-up. We tested the moderating effect of three individual (baseline depressive symptoms, negative attributional style, substance use), three environmental (negative life events, parental support, peer support), and two sociodemographic (sex, age) characteristics. Results: Baseline depressive symptoms interacted with condition and time. Decomposition indicated that elevated baseline depressive symptoms amplified the effect of CB bibliotherapy at posttest (but not 6-month follow-up) relative to the control condition, but did not modify the effect of CB group relative to the control condition or relative to bibliotherapy. Specifically, CB bibliotherapy resulted in lower posttest depressive symptoms than the control condition in individuals with elevated, but not average or low baseline symptoms. We found no interaction effect for other putative moderators. Conclusions: Our findings suggest that bibliotherapy is effective only in participants who have elevated depressive symptoms at baseline. The fact that no study variable moderated the effects of CB group, which had a significant main effect in reducing depressive symptoms relative to the control condition, suggests that this indicated prevention intervention is effective for a wide range of adolescents.

Group-Based Symptom Trajectories in Indicated Prevention of Adolescent Depression

Background: Adolescent depression prevention research has focused on mean intervention outcomes, but has not considered heterogeneity in symptom course. Here, we empirically identify subgroups with distinct trajectories of depressive symptom change among adolescents enrolled in two indicated depression preven- tion trials and examine how cognitive-behavioral (CB) interventions and baseline predictors relate to trajectory membership. Methods: Six hundred thirty-one participants were assigned to one of three conditions: CB group intervention, CB bibliotherapy, and brochure control. We used group-based trajectory modeling to identify trajectories of depressive symptoms from pretest to 2-year follow-up. We examined associations between class membership and conditions using chi- square tests and baseline predictors using multinomial regressions. Results: We identi���ed four trajectories in the full sample. Qualitatively similar trajectories were found in each condition separately. Two trajectories of positive symptom course (low-declining, high-declining) had declining symptoms and were dis- tinguished by baseline symptom severity. Two trajectories of negative course (high-persistent, resurging), respectively, showed no decline in symptoms or de- cline followed by symptom reappearance. Participants in the brochure control condition were signi���cantly more likely to populate the high-persistent trajectory relative to either CB condition and were signi���cantly less likely to populate the low-declining trajectory relative to CB group. Several baseline factors predicted trajectory classes, but gender was the most informative prognostic factor, with males having increased odds of membership in a high-persistent trajectory rel- ative to other trajectories. Conclusions: Findings suggest that CB preventive interventions do not alter the nature of trajectories, but reduce the risk that adolescents follow a trajectory of chronically elevated symptoms.