Review and comparison of effective delayed neutron fraction calculation methods with Monte Carlo codes

The calculation of the effective delayed neutron fraction, beff , with Monte Carlo codes is a complex task due to the requirement of properly considering the adjoint weighting of delayed neutrons. Nevertheless, several techniques have been proposed to circumvent this difficulty and obtain accurate Monte Carlo results for beff without the need of explicitly determining the adjoint flux. In this paper, we make a review of some of these techniques; namely we have analyzed two variants of what we call the k-eigenvalue technique and other techniques based on different interpretations of the physical meaning of the adjoint weighting. To test the validity of all these techniques we have implemented them with the MCNPX code and we have benchmarked them against a range of critical and subcritical systems for which either experimental or deterministic values of beff are available. Furthermore, several nuclear data libraries have been used in order to assess the impact of the uncertainty in nuclear data in the calculated value of beff .

State of the Art and Future Trends in Grid Codes Applicable to Isolated Electrical Systems

Isolated electrical systems lack electrical interconnection to other networks and are usually placed in geographically isolated areas—mainly islands or locations in developing countries. Until recently, only diesel generators were able to assure a safe and reliable supply in exchange for very high costs for fuel transportation and system operation. Transmission system operators (TSOs) are increasingly seeking to replace traditional energy models based on large groups of conventional generation units with mixed solutions where diesel groups are held as backup generation and important advantages are provided by renewable energy sources. The grid codes determine the technical requirements to be fulfilled by the generators connected in any electrical network, but regulations applied to isolated grids are more demanding. In technical literature it is rather easy to find and compare grid codes for interconnected electrical systems. However, the existing literature is incomplete and sparse regarding isolated grids. This paper aims to review the current state of isolated systems and grid codes applicable to them, specifying points of comparison and defining the guidelines to be followed by the upcoming regulations.

Un algoritmo de replanificación en tiempo real basado en un índice de estabilidad de Lyapunov para líneas de metro

(SPA) En este trabajo, se propone un nuevo índice basado en el método directo de Lyapunov para el diseño de un algoritmo de reprogramación en tiempo real para líneas de metro. En este estudio se utiliza una versión modificada de un modelo de espacio de estados en tiempo real discreto, que considera los efectos de saturación en la línea de metro. Una vez que el modelo de espacio de estados se ha obtenido, el método directo de Lyapunov se aplica con el fin de analizar la estabilidad del sistema de la línea de metro. Como resultado de este análisis no sólo se propone un nuevo índice de estabilidad, sino también la creación de tres zonas de estabilidad para indicar el estado actual del sistema. Finalmente, se presenta un nuevo algoritmo que permite la reprogramación del calendario de los trenes en tiempo real en presencia de perturbaciones medianas. (ENG) A new Lyapunov-based index for designing a rescheduling algorithm in real time for metro lines has been proposed in this paper. A modified real time discrete space state model which considers saturation effects in the metro line has been utilized in this study. Once the space state model has been obtained, the direct method of Lyapunov is applied in order to analyze the stability of the metro line system. As a result of this analysis not only a new stability index is proposed, but also the establishment of three stability zones to indicate the current state of the system. Finally, a new algorithm which allows the rescheduling of the timetable in the real time of the trains under presence of medium disturbances has been presented.

Shake-table tests of a reinforced concrete frame designed following modern codes: seismic performance and damage evaluation

This paper presents shake-table tests conducted on a two-fifths-scale reinforced concrete frame representing a conventional construction design under current building code provisions in the Mediterranean area. The structure was subjected to a sequence of dynamic tests including free vibrations and four seismic simulations in which a historical ground motion record was scaled to levels of increasing intensity until collapse. Each seismic simulation was associated with a different level of seismic hazard, representing very frequent, frequent, rare and very rare earthquakes. The structure remained basically undamaged and within the inter-story drift limits of the "immediate occupancy" performance level for the very frequent and frequent earthquakes. For the rare earthquake, the specimen sustained significant damage with chord rotations of up to 28% of its ultimate capacity and approached the upper bound limit of inter-story drift associated with "life safety". The specimen collapsed at the beginning of the "very rare" seismic simulation. Besides summarizing the experimental program, this paper evaluates the damage quantitatively at the global and local levels in terms of chord rotation and other damage indexes, together with the energy dissipation demands for each level of seismic hazard. Further, the ratios of column-to-beam moment capacity recommended by Eurocode 8 and ACI-318 to guarantee the formation of a strong column-weak beam mechanism are examined.

State of the Art and Future Trends in Grid Codes Applicable to Isolated Electrical Systems

Electrical power systems are changing their traditional structure, which was based on a little number of large generating power plants placed at great distances from loads by new models that tend to split the big production nodes in many smaller ones. The set of small groups which are located close to consumers and provide safe and quality energy is called distributed generation (DG). The proximity of the sources to the loads reduces losses associated with transportation and increases overall system efficiency. DG also favors the inclusion of renewable energy sources in isolated electrical systems or remote microgrids, because they can be installed where the natural resource is located. In both cases, as weak grids unable to get help from other nearby networks, it is essential to ensure appropriate behavior of DG sources to guarantee power system safety and stability. The grid codes sets out the technical requirements to be fulfilled for the sources connected in these electrical networks. In technical literature it is rather easy to find and compare grid codes for interconnected electrical systems. However, the existing literature is incomplete and sparse regarding isolated electrical systems and this happens due to the difficulties inherent in the pursuit of codes. Some countries have developed their own legislation only for their island territory (as Spain or France), others apply the same set of rules as in mainland, another group of island countries have elaborated a complete grid code for all generating sources and some others lack specific regulation. This paper aims to make a complete review of the state of the art in grid codes applicable to isolated systems, setting the comparison between them and defining the guidelines predictably followed by the upcoming regulations in these particular systems.

Efficient information reconciliation for Continuous-Variable QKD using Non-Binary Low-Density Parity-Check Codes

We present here an information reconciliation method and demonstrate for the first time that it can achieve efficiencies close to 0.98. This method is based on the belief propagation decoding of non-binary LDPC codes over finite (Galois) fields. In particular, for convenience and faster decoding we only consider power-of-two Galois fields.

Madrid 1919, un nuevo escenario urbano subterráneo: el Metro. Aparición en España del concepto de viaje sin referencias espaciales.

Esta comunicación recibió la condición especial de ser destacada por el Comité Científico. A comienzos del siglo XX se empieza a implantar un novedoso medio de transporte en las grandes ciudades españolas: el metro. Aunque ya se había probado con éxito en otras ciudades europeas (Londres, Viena, París?), la expectación surgida en la capital era desmedida. En aquellos años Madrid se encontraba inmersa en un importante proceso de transformación que la convertiría décadas más tarde en una gran metrópoli. No obstante, en estos años de definición de su propia trama urbana la ciudad estaba colapsada por los tranvías y el creciente tráfico de automóviles. La Compañía Metropolitano Alfonso XIII, fundada por los ingenieros Miguel Otamendi, Antonio G. Echarte y Carlos Mendoza, consiguió materializar en un eficaz proyecto la idea de un nuevo tipo de transporte que discurría por debajo del nivel de calle. Este tipo de ferrocarril subterráneo planteó la aparición de unos nuevos parámetros espaciales que modificaron la percepción que los viajeros urbanos tenían de la metrópoli. Las bocas de metro se convirtieron enseguida en hitos en torno a los cuales se podían tomar referencias y orientarse en la trama urbana. La descontextualización del viaje respecto al entorno físico en el cual se produce ese desplazamiento direccional convirtió la experiencia de viajar a través del subsuelo en algo futurista para la época. Y con ello cambió la concepción de la ciudad, dejamos de percibirla en su totalidad para experimentarla de manera fragmentada por esos lapsos de tiempo que transcurren entre la entrada y la salida del metro. A través de los dibujos que Antonio Palacios Ramilo (Porriño 1874 ? Madrid 1945), arquitecto oficial de la Compañía, realizó para el diseño de las estaciones, vestíbulos y bocas de acceso podemos sentir la búsqueda constante de calidez y luminosidad como contraste frente a la imagen estereotipada fría y oscura de una caverna excavada bajo tierra. La introducción de la luz cenital en los vestíbulos, el recubrimiento de todas las superficies de tránsito con azulejos blancos que reflejan y multiplican la luz y el exquisito diseño de todos los detalles demuestran el interés del arquitecto por dignificar en todo momento estos nuevos espacios subterráneos, caracterizando con una identidad propia esta nueva tipología arquitectónica, y convirtiendo el viaje en metro en una experiencia sensorial innovadora. Abstract: n the early twentieth century Madrid was undergoing a major transformation that would make decades later in a large metropolis. However, in these years of defining its own urban grid the city was jammed with trams and the increasing car traffic. In 1919, the Com- pany Metropolitan Alfonso XIII, got into an effective project materialize the idea of a new type of transport that ran below the calle. Analizaremos experience as a paradigm shift in the trip meter without spatial reference. We will study the elements of this under- ground network and the relationships between them are generated: nodes , flows, transit spaces, waiting areas and up... And finally , will point to what extent the construction of this transport has influenced and modified the urban scene on the slope where the meter has become an element of our everyday life.

Antonio Palacios y el ferrocarril metropolitano. Patrimonio Industrial en el Metro de Madrid

Antonio Palacios Ramilo, relevante arquitecto de la 1ª mitad del siglo XX, responsable de emblemáticos edificios del centro de la capital (Círculo de Bellas Artes, Palacio de Correos...), es también autor de otro tipo de arquitectura mucho menos conocida. En su calidad de arquitecto oficial de la Compañía Metropolitana Alfonso XIII, diseñó no sólo las estaciones, bocas y templetes del metro de Madrid, sino también toda una serie de edificios auxiliares entre los que destacan las centrales y subestaciones eléctricas. Analizaremos, por tanto, el modo de intervención de Palacios en la arquitectura industrial respecto al resto de su obra y estudiaremos el estado en que se encuentra actualmente este patrimonio, distinguiendo entre los casos en los que ha habido una intervención restauradora (Nave de Motores en Pacífico, Estación de Chamberí), los que están en desuso (subestaciones de Quevedo y Salamanca...) y los elementos que ya han desaparecido (templetes de Sol y Gran Vía).

Proyecto de construcción de la línea de Metro Ligero: tramo Monterrozas-Las Rozas

El presente Proyecto Constructivo define las obras necesarias para la construcción de la infraestructura de la línea de Metro Ligero Monterrozas- Las Rozas. La línea comienza discurriendo por el bulevar central de la Calle Camilo José Cela, donde efectúa dos paradas. La primera se encuentra a la altura de la Biblioteca Leon Tolstoi, mientras que la segunda se sitúa entre el Heron City y Las Rozas Village. Se diseña así la línea de transporte guiado urbano tipo metro ligero, y la definición alcanza todas las obras precisas para su ejecución: demoliciones, movimiento de tierras, urbanización y viales, estructuras, obras subterráneas, subestaciones (obra civil), drenaje, integración ambiental, paradas y estaciones, plataforma y superestructura, desvíos de tráfico, reposición de servicios afectados y obras complementarias