14 resultados para Neighbours and Neighbourhood

em Universidad Politécnica de Madrid


Relevância:

90.00% 90.00%

Publicador:

Resumo:

La relación entre la estructura urbana y la movilidad ha sido estudiada desde hace más de 70 años. El entorno urbano incluye múltiples dimensiones como por ejemplo: la estructura urbana, los usos de suelo, la distribución de instalaciones diversas (comercios, escuelas y zonas de restauración, parking, etc.). Al realizar una revisión de la literatura existente en este contexto, se encuentran distintos análisis, metodologías, escalas geográficas y dimensiones, tanto de la movilidad como de la estructura urbana. En este sentido, se trata de una relación muy estudiada pero muy compleja, sobre la que no existe hasta el momento un consenso sobre qué dimensión del entorno urbano influye sobre qué dimensión de la movilidad, y cuál es la manera apropiada de representar esta relación. Con el propósito de contestar estas preguntas investigación, la presente tesis tiene los siguientes objetivos generales: (1) Contribuir al mejor entendimiento de la compleja relación estructura urbana y movilidad. y (2) Entender el rol de los atributos latentes en la relación entorno urbano y movilidad. El objetivo específico de la tesis es analizar la influencia del entorno urbano sobre dos dimensiones de la movilidad: número de viajes y tipo de tour. Vista la complejidad de la relación entorno urbano y movilidad, se pretende contribuir al mejor entendimiento de la relación a través de la utilización de 3 escalas geográficas de las variables y del análisis de la influencia de efectos inobservados en la movilidad. Para el análisis se utiliza una base de datos conformada por tres tipos de datos: (1) Una encuesta de movilidad realizada durante los años 2006 y 2007. Se obtuvo un total de 943 encuestas, en 3 barrios de Madrid: Chamberí, Pozuelo y Algete. (2) Información municipal del Instituto Nacional de Estadística: dicha información se encuentra enlazada con los orígenes y destinos de los viajes recogidos en la encuesta. Y (3) Información georeferenciada en Arc-GIS de los hogares participantes en la encuesta: la base de datos contiene información respecto a la estructura de las calles, localización de escuelas, parking, centros médicos y lugares de restauración. Se analizó la correlación entre e intra-grupos y se modelizaron 4 casos de atributos bajo la estructura ordinal logit. Posteriormente se evalúa la auto-selección a través de la estimación conjunta de las elecciones de tipo de barrio y número de viajes. La elección del tipo de barrio consta de 3 alternativas: CBD, Urban y Suburban, según la zona de residencia recogida en las encuestas. Mientras que la elección del número de viajes consta de 4 categorías ordinales: 0 viajes, 1-2 viajes, 3-4 viajes y 5 o más viajes. A partir de la mejor especificación del modelo ordinal logit. Se desarrolló un modelo joint mixed-ordinal conjunto. Los resultados indican que las variables exógenas requieren un análisis exhaustivo de correlaciones con el fin de evitar resultados sesgados. ha determinado que es importante medir los atributos del BE donde se realiza el viaje, pero también la información municipal es muy explicativa de la movilidad individual. Por tanto, la percepción de las zonas de destino a nivel municipal es considerada importante. En el contexto de la Auto-selección (self-selection) es importante modelizar conjuntamente las decisiones. La Auto-selección existe, puesto que los parámetros estimados conjuntamente son significativos. Sin embargo, sólo ciertos atributos del entorno urbano son igualmente importantes sobre la elección de la zona de residencia y frecuencia de viajes. Para analizar la Propensión al Viaje, se desarrolló un modelo híbrido, formado por: una variable latente, un indicador y un modelo de elección discreta. La variable latente se denomina “Propensión al Viaje”, cuyo indicador en ecuación de medida es el número de viajes; la elección discreta es el tipo de tour. El modelo de elección consiste en 5 alternativas, según la jerarquía de actividades establecida en la tesis: HOME, no realiza viajes durante el día de estudio, HWH tour cuya actividad principal es el trabajo o estudios, y no se realizan paradas intermedias; HWHs tour si el individuo reaiza paradas intermedias; HOH tour cuya actividad principal es distinta a trabajo y estudios, y no se realizan paradas intermedias; HOHs donde se realizan paradas intermedias. Para llegar a la mejor especificación del modelo, se realizó un trabajo importante considerando diferentes estructuras de modelos y tres tipos de estimaciones. De tal manera, se obtuvieron parámetros consistentes y eficientes. Los resultados muestran que la modelización de los tours, representa una ventaja sobre la modelización de los viajes, puesto que supera las limitaciones de espacio y tiempo, enlazando los viajes realizados por la misma persona en el día de estudio. La propensión al viaje (PT) existe y es específica para cada tipo de tour. Los parámetros estimados en el modelo híbrido resultaron significativos y distintos para cada alternativa de tipo de tour. Por último, en la tesis se verifica que los modelos híbridos representan una mejora sobre los modelos tradicionales de elección discreta, dando como resultado parámetros consistentes y más robustos. En cuanto a políticas de transporte, se ha demostrado que los atributos del entorno urbano son más importantes que los LOS (Level of Service) en la generación de tours multi-etapas. la presente tesis representa el primer análisis empírico de la relación entre los tipos de tours y la propensión al viaje. El concepto Propensity to Travel ha sido desarrollado exclusivamente para la tesis. Igualmente, el desarrollo de un modelo conjunto RC-Number of trips basado en tres escalas de medida representa innovación en cuanto a la comparación de las escalas geográficas, que no había sido hecha en la modelización de la self-selection. The relationship between built environment (BE) and travel behaviour (TB) has been studied in a number of cases, using several methods - aggregate and disaggregate approaches - and different focuses – trip frequency, automobile use, and vehicle miles travelled and so on. Definitely, travel is generated by the need to undertake activities and obtain services, and there is a general consensus that urban components affect TB. However researches are still needed to better understand which components of the travel behaviour are affected most and by which of the urban components. In order to fill the gap in the research, the present dissertation faced two main objectives: (1) To contribute to the better understanding of the relationship between travel demand and urban environment. And (2) To develop an econometric model for estimating travel demand with urban environment attributes. With this purpose, the present thesis faced an exhaustive research and computation of land-use variables in order to find the best representation of BE for modelling trip frequency. In particular two empirical analyses are carried out: 1. Estimation of three dimensions of travel demand using dimensions of urban environment. We compare different travel dimensions and geographical scales, and we measure self-selection contribution following the joint models. 2. Develop a hybrid model, integrated latent variable and discrete choice model. The implementation of hybrid models is new in the analysis of land-use and travel behaviour. BE and TB explicitly interact and allow richness information about a specific individual decision process For all empirical analysis is used a data-base from a survey conducted in 2006 and 2007 in Madrid. Spatial attributes describing neighbourhood environment are derived from different data sources: National Institute of Statistics-INE (Administrative: municipality and district) and GIS (circular units). INE provides raw data for such spatial units as: municipality and district. The construction of census units is trivial as the census bureau provides tables that readily define districts and municipalities. The construction of circular units requires us to determine the radius and associate the spatial information to our households. The first empirical part analyzes trip frequency by applying an ordered logit model. In this part is studied the effect of socio-economic, transport and land use characteristics on two travel dimensions: trip frequency and type of tour. In particular the land use is defined in terms of type of neighbourhoods and types of dwellers. Three neighbourhood representations are explored, and described three for constructing neighbourhood attributes. In particular administrative units are examined to represent neighbourhood and circular – unit representation. Ordered logit models are applied, while ordinal logit models are well-known, an intensive work for constructing a spatial attributes was carried out. On the other hand, the second empirical analysis consists of the development of an innovative econometric model that considers a latent variable called “propensity to travel”, and choice model is the choice of type of tour. The first two specifications of ordinal models help to estimate this latent variable. The latent variable is unobserved but the manifestation is called “indicators”, then the probability of choosing an alternative of tour is conditional to the probability of latent variable and type of tour. Since latent variable is unknown we fit the integral over its distribution. Four “sets of best variables” are specified, following the specification obtained from the correlation analysis. The results evidence that the relative importance of SE variables versus BE variables depends on how BE variables are measured. We found that each of these three spatial scales has its intangible qualities and drawbacks. Spatial scales play an important role on predicting travel demand due to the variability in measures at trip origin/destinations within the same administrative unit (municipality, district and so on). Larger units will produce less variation in data; but it does not affect certain variables, such as public transport supply, that are more significant at municipality level. By contrast, land-use measures are more efficient at district level. Self-selection in this context, is weak. Thus, the influence of BE attributes is true. The results of the hybrid model show that unobserved factors affect the choice of tour complexity. The latent variable used in this model is propensity to travel that is explained by socioeconomic aspects and neighbourhood attributes. The results show that neighbourhood attributes have indeed a significant impact on the choice of the type of tours either directly and through the propensity to travel. The propensity to travel has a different impact depending on the structure of each tour and increases the probability of choosing more complex tours, such as tours with many intermediate stops. The integration of choice and latent variable model shows that omitting important perception and attitudes leads to inconsistent estimates. The results also indicate that goodness of fit improves by adding the latent variable in both sequential and simultaneous estimation. There are significant differences in the sensitivity to the latent variable across alternatives. In general, as expected, the hybrid models show a major improvement into the goodness of fit of the model, compared to a classical discrete choice model that does not incorporate latent effects. The integrated model leads to a more detailed analysis of the behavioural process. Summarizing, the effect that built environment characteristics on trip frequency studied is deeply analyzed. In particular we tried to better understand how land use characteristics can be defined and measured and which of these measures do have really an impact on trip frequency. We also tried to test the superiority of HCM on this field. We can concluded that HCM shows a major improvement into the goodness of fit of the model, compared to classical discrete choice model that does not incorporate latent effects. And consequently, the application of HCM shows the importance of LV on the decision of tour complexity. People are more elastic to built environment attributes than level of services. Thus, policy implications must take place to develop more mixed areas, work-places in combination with commercial retails.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Esta tesis analiza las acciones de los pobladores en la creación, consolidación y transformación de su hábitat y en su relación con la política pública de vivienda y barrio en Chile. A partir de la observación directa en terreno y de la revisión de material proveniente de diversas fuentes afirmamos que, aunque los pobladores han hecho un trabajo de producción del hábitat de gran magnitud y generalizado, las políticas públicas no han reconocido suficientemente su papel en la construcción de la ciudad, no han incorporado a cabalidad las potencialidades e innovaciones surgidas de sus prácticas y estrategias, y nunca les han abierto un espacio claro en la toma de decisiones y en la puesta en obra de los programas habitacionales. En el contexto latinoamericano, la política habitacional chilena de los últimos 20 años se ha considerado un éxito y un ejemplo a seguir, puesto que ha demostrado ser eficaz en la disminución del déficit habitacional. Sin embargo, ha tenido efectos urbanos y sociales nefastos, como la construcción de extensos bolsones periféricos de pobreza que se degradan aceleradamente, y la desintegración social que genera la expulsión de los sin casa a la periferia, donde pierden sus redes familiares y sociales. Desde una trinchera opuesta, los allegados, los sin casa que viven al alero de otras familias y representan la mayoría de la demanda por vivienda, exigen quedarse en barrios ya consolidados y evitan las periferias, en parte por mantener una red familiar y social que se sustenta en la proximidad física, en parte por los equipamientos y servicios con que cuentan estos barrios y la cercanía a las fuentes de empleo. Al mismo tiempo, los responsables de diseñar la política habitacional no han buscado establecer una forma de colaboración con los pobladores —principales receptores de la política— con el fin ajustar los programas públicos a las necesidades de las familias de bajos ingresos y a las realidades socioculturales de sus barrios. Por el contrario, han privilegiado una alianza con el sector privado, que conoce muy limitadamente las demandas de las familias. Así, en lugar de construir ciudades más justas, la política habitacional ha alimentado un mercado inmobiliario sustentado en la especulación del suelo y fomentado la industria de la construcción. La pregunta que guía esta investigación es cómo incorporar el conocimiento acumulado y los procedimientos probados por los pobladores al diseño y la implementación de programas habitacionales y urbanos que promuevan procesos de regeneración de las poblaciones y mejoren la distribución de la vivienda social en la ciudad. Sostenemos que los pobladores, a lo largo de una trayectoria de más de medio siglo, han adquirido y consolidado todas las competencias para construir vivienda, mejorar sus barrios e incorporarse a la discusión sobre ordenamiento territorial. Así, hoy están capacitados para asumir un papel protagónico en la definición de políticas públicas que apunte a la construcción de ciudades más sostenibles y equitativas. La producción social del hábitat vinculada al derecho a la ciudad y a la participación de los pobladores «desde abajo» está bastante documentada en la literatura latinoamericana. En Chile se han escrito numerosos trabajos y evaluaciones sobre la política habitacional, pero los estudios sobre el movimiento de pobladores, enfocados desde las ciencias sociales o multidisciplinares, tienen un auge primero, durante los años 60 y principios de los 70 y luego, en la segunda mitad de los 80, pero posteriormente dejan de publicarse, a excepción de algunas investigaciones de historia urbana o social. En cuanto a los estudios que abordan las acciones de los pobladores desde una mirada puesta en los resultados de la producción y la gestión habitacional y urbana, estos han sido especialmente escasos y ninguno abarca un período largo. La tesis aborda entonces las acciones específicas que emprenden los pobladores a distintas escalas territoriales —el conjunto, el barrio, la población, la ciudad y el país—, su relación con la política habitacional y su articulación con los demás actores que intervienen en la producción material del hábitat. Lo realizado por los pobladores se estudia a la luz del largo plazo, desde la promulgación de la primera ley de vivienda en 1906 hasta nuestros días, con el énfasis puesto entre los años 1990 y 2010, período de producción masiva y sostenida de vivienda social, financiada por el Estado y construida por el sector privado en la periferia urbana, y más detalladamente entre 2006 y 2010, cuando los pobladores irrumpen con la «gestión vecinal» y la «autogestión» como medios para implementar los programas habitacionales del gobierno. Para ello se recorre toda la trayectoria y se complementa con procesos particulares, a la manera de un lente de acercamiento con el cual se focalizan y amplifican trece casos de estudios, para ilustrar modos de producción y gestión concretos y mostrar cómo estos se inscriben en modos de hacer genéricos de los pobladores. Finalmente, con el lente centrado en el último ciclo de este proceso escribimos el capítulo inédito de los últimos veinte años de esta historia. Primero se realiza la reconstrucción de tres casos de estudio «en profundidad», que incluyen la génesis, la consolidación y las transformaciones del conjunto o barrio. Estos casos de estudio «en profundidad» se ponen en perspectiva reconstruyendo la trayectoria histórica de la producción y gestión realizada por los pobladores. Esta reconstrucción de largo período se profundiza con tres casos de estudio «específicos», de dimensión histórica, que tratan el conflicto del acceso a suelo. Finalmente se analizan las interrogantes que plantean estos procesos hoy en día para la producción y gestión de vivienda y barrio a futuro, a partir de entrevistas a actores claves y de la reconstrucción de siete casos de estudio «específicos» de acceso a suelo ilustrativos del período actual. La tesis sustenta que los pobladores, con las acciones de gestión y autogestión que realizan desde 2006, e interviniendo en la discusión sobre los instrumentos de planificación territorial a partir del mismo año, se sitúan actualmente en una nueva plataforma de acción y negociación desde la cual pueden incorporarse, con todas las competencias necesarias, a la definición de las políticas públicas y así dotarlas de pertinencia y coherencia para contribuir a superar la pobreza con respuestas más acorde a sus realidades. ABSTRACT This thesis analyzes the actions of pobladores in the creation, consolidation and transformation of their habitat and their relationship with Chilean public housing and neighbourhood policy. Through direct observation in the field and the review of material from various sources we can affirm that although the pobladores have undertaken widespread work in the production of their environment, public policies have not sufficiently recognized their role in the construction of the city. Public policy has failed to fully incorporate the potential and innovation arising from practices and strategies employed by social housing recipients and has never opened a clear space for them in decision-making or the commissioning work of the housing programs. Within the Latin America context, the Chilean housing policy of the past 20 years has been considered a success and an example to follow given that it has proven effective in reducing the housing deficit. However it has had disastrous urban and social effects, such as construction of large peripheral pockets of poverty that degrade rapidly, and generates social disintegration through the expulsion of the homeless to the periphery, where they lose their family and social networks. On another front those homeless who live under the roof of relatives and who represent the majority of demand for social housing, request to stay in consolidated neighbourhoods avoiding the periphery, partly to maintain family and social networks based on physical proximity and partly because of the facilities and services available in these neighbourhoods and their adjacency to sources of employment. At the same time, those responsible for designing housing policy have not sought to establish a form of collaboration with the pobladores in order to adjust the public programs to the needs of low-income families and the socio-cultural realities of their neighbourhoods. On the contrary an alliance with the private sector has been favored, a sector which has very limited knowledge of the demands of the recipients. Therefore instead of building more equal cities, housing policy has fueled a housing market which supports land speculation and promotes the construction industry. The question leading this research is how to incorporate the accumulated knowledge and proven procedures of the pobladores in the design and implementation of programs that promote housing and urban regeneration processes and which could improve the distribution of social housing in the city. We maintain that social housing recipients over the course of half a century have acquired and consolidated all the skills to build housing, improve neighborhoods and join the discussion on city planning. These residents are now capable of assuming a leading role in defining public policies that aim to build more sustainable and equitable cities. The social production of the environment linked to the right to the city and resident participation from the «bottom-up» is well documented in Latin American literature. In Chile there are extensive written works and assessments on housing policy with multidisciplinary or social science studies on the movement of the pobladores peaking during the 60’s and early 70’s and then again in the second half of the 80’s but afterwards this stops, with the exception of some research on social or urban history. As for studies that address the actions of the pobladores looking at the results of production and housing and urban management these have been particularly scarce and none of which cover a long period of time. The thesis then addresses the specific actions undertaken by the pobladores at different territorial levels; the housing development, the neighbourhood, the community, the city and State, and their relation to housing policy and its coordination with other actors involved in the production process of the built environment. The accomplishments of the pobladores is studied over the long term, since the enactment of the first housing law in 1906 to the present, with an emphasis between 1990 and 2010, a period of mass production and sustained social housing which was State-funded and built by the private sector in the urban periphery, and in particular between 2006 and 2010, when the pobladores break with the «neighborhood management» and «self-management» as a means to implement the housing programs of the government. To this end the entire process is outlined and is complemented by specific processes which are placed under a lens in order to focus and amplify thirteen case studies illustrating actual ways of production and management and to show how these ways of doing things are generic to the pobladores. Finally, with the lens focused on the last cycle of this process we write the new chapter of the last twenty years of this history. First there is a reconstruction of three case studies «in depth», including their origins, consolidation and the transformation of the sector or neighborhood. These «in depth» case studies are put into perspective reconstructing the historical trajectory of the production and management by the pobladores. This reconstruction over a long period is given great depth by three «specific» case studies, of historical importance, dealing with the conflict of access to land. Finally we analyze the questions raised by these processes for the production and management of housing and neighborhood in the future, based on interviews with key players and the reconstruction of seven case studies specifically regarding access to land and which are illustrative of current practice. The thesis maintains that since 2006 the pobladores through actions of management and selfmanagement and their intervention in the debate on territorial planning has placed them on a new platform for action and negotiation from which they can incorporate themselves, with all the necessary capacities, in the definition of public policy and therefore provide it with a pertinence and coherence to help towards overcoming poverty with answers more according to their realities.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

La astronomía de rayos γ estudia las partículas más energéticas que llegan a la Tierra desde el espacio. Estos rayos γ no se generan mediante procesos térmicos en simples estrellas, sino mediante mecanismos de aceleración de partículas en objetos celestes como núcleos de galaxias activos, púlsares, supernovas, o posibles procesos de aniquilación de materia oscura. Los rayos γ procedentes de estos objetos y sus características proporcionan una valiosa información con la que los científicos tratan de comprender los procesos físicos que ocurren en ellos y desarrollar modelos teóricos que describan su funcionamiento con fidelidad. El problema de observar rayos γ es que son absorbidos por las capas altas de la atmósfera y no llegan a la superficie (de lo contrario, la Tierra será inhabitable). De este modo, sólo hay dos formas de observar rayos γ embarcar detectores en satélites, u observar los efectos secundarios que los rayos γ producen en la atmósfera. Cuando un rayo γ llega a la atmósfera, interacciona con las partículas del aire y genera un par electrón - positrón, con mucha energía. Estas partículas secundarias generan a su vez más partículas secundarias cada vez menos energéticas. Estas partículas, mientras aún tienen energía suficiente para viajar más rápido que la velocidad de la luz en el aire, producen una radiación luminosa azulada conocida como radiación Cherenkov durante unos pocos nanosegundos. Desde la superficie de la Tierra, algunos telescopios especiales, conocidos como telescopios Cherenkov o IACTs (Imaging Atmospheric Cherenkov Telescopes), son capaces de detectar la radiación Cherenkov e incluso de tomar imágenes de la forma de la cascada Cherenkov. A partir de estas imágenes es posible conocer las principales características del rayo γ original, y con suficientes rayos se pueden deducir características importantes del objeto que los emitió, a cientos de años luz de distancia. Sin embargo, detectar cascadas Cherenkov procedentes de rayos γ no es nada fácil. Las cascadas generadas por fotones γ de bajas energías emiten pocos fotones, y durante pocos nanosegundos, y las correspondientes a rayos γ de alta energía, si bien producen más electrones y duran más, son más improbables conforme mayor es su energía. Esto produce dos líneas de desarrollo de telescopios Cherenkov: Para observar cascadas de bajas energías son necesarios grandes reflectores que recuperen muchos fotones de los pocos que tienen estas cascadas. Por el contrario, las cascadas de altas energías se pueden detectar con telescopios pequeños, pero conviene cubrir con ellos una superficie grande en el suelo para aumentar el número de eventos detectados. Con el objetivo de mejorar la sensibilidad de los telescopios Cherenkov actuales, en el rango de energía alto (> 10 TeV), medio (100 GeV - 10 TeV) y bajo (10 GeV - 100 GeV), nació el proyecto CTA (Cherenkov Telescope Array). Este proyecto en el que participan más de 27 países, pretende construir un observatorio en cada hemisferio, cada uno de los cuales contará con 4 telescopios grandes (LSTs), unos 30 medianos (MSTs) y hasta 70 pequeños (SSTs). Con un array así, se conseguirán dos objetivos. En primer lugar, al aumentar drásticamente el área de colección respecto a los IACTs actuales, se detectarán más rayos γ en todos los rangos de energía. En segundo lugar, cuando una misma cascada Cherenkov es observada por varios telescopios a la vez, es posible analizarla con mucha más precisión gracias a las técnicas estereoscópicas. La presente tesis recoge varios desarrollos técnicos realizados como aportación a los telescopios medianos y grandes de CTA, concretamente al sistema de trigger. Al ser las cascadas Cherenkov tan breves, los sistemas que digitalizan y leen los datos de cada píxel tienen que funcionar a frecuencias muy altas (≈1 GHz), lo que hace inviable que funcionen de forma continua, ya que la cantidad de datos guardada será inmanejable. En su lugar, las señales analógicas se muestrean, guardando las muestras analógicas en un buffer circular de unos pocos µs. Mientras las señales se mantienen en el buffer, el sistema de trigger hace un análisis rápido de las señales recibidas, y decide si la imagen que hay en el buér corresponde a una cascada Cherenkov y merece ser guardada, o por el contrario puede ignorarse permitiendo que el buffer se sobreescriba. La decisión de si la imagen merece ser guardada o no, se basa en que las cascadas Cherenkov producen detecciones de fotones en píxeles cercanos y en tiempos muy próximos, a diferencia de los fotones de NSB (night sky background), que llegan aleatoriamente. Para detectar cascadas grandes es suficiente con comprobar que más de un cierto número de píxeles en una región hayan detectado más de un cierto número de fotones en una ventana de tiempo de algunos nanosegundos. Sin embargo, para detectar cascadas pequeñas es más conveniente tener en cuenta cuántos fotones han sido detectados en cada píxel (técnica conocida como sumtrigger). El sistema de trigger desarrollado en esta tesis pretende optimizar la sensibilidad a bajas energías, por lo que suma analógicamente las señales recibidas en cada píxel en una región de trigger y compara el resultado con un umbral directamente expresable en fotones detectados (fotoelectrones). El sistema diseñado permite utilizar regiones de trigger de tamaño seleccionable entre 14, 21 o 28 píxeles (2, 3, o 4 clusters de 7 píxeles cada uno), y con un alto grado de solapamiento entre ellas. De este modo, cualquier exceso de luz en una región compacta de 14, 21 o 28 píxeles es detectado y genera un pulso de trigger. En la versión más básica del sistema de trigger, este pulso se distribuye por toda la cámara de forma que todos los clusters sean leídos al mismo tiempo, independientemente de su posición en la cámara, a través de un delicado sistema de distribución. De este modo, el sistema de trigger guarda una imagen completa de la cámara cada vez que se supera el número de fotones establecido como umbral en una región de trigger. Sin embargo, esta forma de operar tiene dos inconvenientes principales. En primer lugar, la cascada casi siempre ocupa sólo una pequeña zona de la cámara, por lo que se guardan muchos píxeles sin información alguna. Cuando se tienen muchos telescopios como será el caso de CTA, la cantidad de información inútil almacenada por este motivo puede ser muy considerable. Por otro lado, cada trigger supone guardar unos pocos nanosegundos alrededor del instante de disparo. Sin embargo, en el caso de cascadas grandes la duración de las mismas puede ser bastante mayor, perdiéndose parte de la información debido al truncamiento temporal. Para resolver ambos problemas se ha propuesto un esquema de trigger y lectura basado en dos umbrales. El umbral alto decide si hay un evento en la cámara y, en caso positivo, sólo las regiones de trigger que superan el nivel bajo son leídas, durante un tiempo más largo. De este modo se evita guardar información de píxeles vacíos y las imágenes fijas de las cascadas se pueden convertir en pequeños \vídeos" que representen el desarrollo temporal de la cascada. Este nuevo esquema recibe el nombre de COLIBRI (Concept for an Optimized Local Image Building and Readout Infrastructure), y se ha descrito detalladamente en el capítulo 5. Un problema importante que afecta a los esquemas de sumtrigger como el que se presenta en esta tesis es que para sumar adecuadamente las señales provenientes de cada píxel, estas deben tardar lo mismo en llegar al sumador. Los fotomultiplicadores utilizados en cada píxel introducen diferentes retardos que deben compensarse para realizar las sumas adecuadamente. El efecto de estos retardos ha sido estudiado, y se ha desarrollado un sistema para compensarlos. Por último, el siguiente nivel de los sistemas de trigger para distinguir efectivamente las cascadas Cherenkov del NSB consiste en buscar triggers simultáneos (o en tiempos muy próximos) en telescopios vecinos. Con esta función, junto con otras de interfaz entre sistemas, se ha desarrollado un sistema denominado Trigger Interface Board (TIB). Este sistema consta de un módulo que irá montado en la cámara de cada LST o MST, y que estará conectado mediante fibras ópticas a los telescopios vecinos. Cuando un telescopio tiene un trigger local, este se envía a todos los vecinos conectados y viceversa, de modo que cada telescopio sabe si sus vecinos han dado trigger. Una vez compensadas las diferencias de retardo debidas a la propagación en las fibras ópticas y de los propios fotones Cherenkov en el aire dependiendo de la dirección de apuntamiento, se buscan coincidencias, y en el caso de que la condición de trigger se cumpla, se lee la cámara en cuestión, de forma sincronizada con el trigger local. Aunque todo el sistema de trigger es fruto de la colaboración entre varios grupos, fundamentalmente IFAE, CIEMAT, ICC-UB y UCM en España, con la ayuda de grupos franceses y japoneses, el núcleo de esta tesis son el Level 1 y la Trigger Interface Board, que son los dos sistemas en los que que el autor ha sido el ingeniero principal. Por este motivo, en la presente tesis se ha incluido abundante información técnica relativa a estos sistemas. Existen actualmente importantes líneas de desarrollo futuras relativas tanto al trigger de la cámara (implementación en ASICs), como al trigger entre telescopios (trigger topológico), que darán lugar a interesantes mejoras sobre los diseños actuales durante los próximos años, y que con suerte serán de provecho para toda la comunidad científica participante en CTA. ABSTRACT -ray astronomy studies the most energetic particles arriving to the Earth from outer space. This -rays are not generated by thermal processes in mere stars, but by means of particle acceleration mechanisms in astronomical objects such as active galactic nuclei, pulsars, supernovas or as a result of dark matter annihilation processes. The γ rays coming from these objects and their characteristics provide with valuable information to the scientist which try to understand the underlying physical fundamentals of these objects, as well as to develop theoretical models able to describe them accurately. The problem when observing rays is that they are absorbed in the highest layers of the atmosphere, so they don't reach the Earth surface (otherwise the planet would be uninhabitable). Therefore, there are only two possible ways to observe γ rays: by using detectors on-board of satellites, or by observing their secondary effects in the atmosphere. When a γ ray reaches the atmosphere, it interacts with the particles in the air generating a highly energetic electron-positron pair. These secondary particles generate in turn more particles, with less energy each time. While these particles are still energetic enough to travel faster than the speed of light in the air, they produce a bluish radiation known as Cherenkov light during a few nanoseconds. From the Earth surface, some special telescopes known as Cherenkov telescopes or IACTs (Imaging Atmospheric Cherenkov Telescopes), are able to detect the Cherenkov light and even to take images of the Cherenkov showers. From these images it is possible to know the main parameters of the original -ray, and with some -rays it is possible to deduce important characteristics of the emitting object, hundreds of light-years away. However, detecting Cherenkov showers generated by γ rays is not a simple task. The showers generated by low energy -rays contain few photons and last few nanoseconds, while the ones corresponding to high energy -rays, having more photons and lasting more time, are much more unlikely. This results in two clearly differentiated development lines for IACTs: In order to detect low energy showers, big reflectors are required to collect as much photons as possible from the few ones that these showers have. On the contrary, small telescopes are able to detect high energy showers, but a large area in the ground should be covered to increase the number of detected events. With the aim to improve the sensitivity of current Cherenkov showers in the high (> 10 TeV), medium (100 GeV - 10 TeV) and low (10 GeV - 100 GeV) energy ranges, the CTA (Cherenkov Telescope Array) project was created. This project, with more than 27 participating countries, intends to build an observatory in each hemisphere, each one equipped with 4 large size telescopes (LSTs), around 30 middle size telescopes (MSTs) and up to 70 small size telescopes (SSTs). With such an array, two targets would be achieved. First, the drastic increment in the collection area with respect to current IACTs will lead to detect more -rays in all the energy ranges. Secondly, when a Cherenkov shower is observed by several telescopes at the same time, it is possible to analyze it much more accurately thanks to the stereoscopic techniques. The present thesis gathers several technical developments for the trigger system of the medium and large size telescopes of CTA. As the Cherenkov showers are so short, the digitization and readout systems corresponding to each pixel must work at very high frequencies (_ 1 GHz). This makes unfeasible to read data continuously, because the amount of data would be unmanageable. Instead, the analog signals are sampled, storing the analog samples in a temporal ring buffer able to store up to a few _s. While the signals remain in the buffer, the trigger system performs a fast analysis of the signals and decides if the image in the buffer corresponds to a Cherenkov shower and deserves to be stored, or on the contrary it can be ignored allowing the buffer to be overwritten. The decision of saving the image or not, is based on the fact that Cherenkov showers produce photon detections in close pixels during near times, in contrast to the random arrival of the NSB phtotons. Checking if more than a certain number of pixels in a trigger region have detected more than a certain number of photons during a certain time window is enough to detect large showers. However, taking also into account how many photons have been detected in each pixel (sumtrigger technique) is more convenient to optimize the sensitivity to low energy showers. The developed trigger system presented in this thesis intends to optimize the sensitivity to low energy showers, so it performs the analog addition of the signals received in each pixel in the trigger region and compares the sum with a threshold which can be directly expressed as a number of detected photons (photoelectrons). The trigger system allows to select trigger regions of 14, 21, or 28 pixels (2, 3 or 4 clusters with 7 pixels each), and with extensive overlapping. In this way, every light increment inside a compact region of 14, 21 or 28 pixels is detected, and a trigger pulse is generated. In the most basic version of the trigger system, this pulse is just distributed throughout the camera in such a way that all the clusters are read at the same time, independently from their position in the camera, by means of a complex distribution system. Thus, the readout saves a complete camera image whenever the number of photoelectrons set as threshold is exceeded in a trigger region. However, this way of operating has two important drawbacks. First, the shower usually covers only a little part of the camera, so many pixels without relevant information are stored. When there are many telescopes as will be the case of CTA, the amount of useless stored information can be very high. On the other hand, with every trigger only some nanoseconds of information around the trigger time are stored. In the case of large showers, the duration of the shower can be quite larger, loosing information due to the temporal cut. With the aim to solve both limitations, a trigger and readout scheme based on two thresholds has been proposed. The high threshold decides if there is a relevant event in the camera, and in the positive case, only the trigger regions exceeding the low threshold are read, during a longer time. In this way, the information from empty pixels is not stored and the fixed images of the showers become to little \`videos" containing the temporal development of the shower. This new scheme is named COLIBRI (Concept for an Optimized Local Image Building and Readout Infrastructure), and it has been described in depth in chapter 5. An important problem affecting sumtrigger schemes like the one presented in this thesis is that in order to add the signals from each pixel properly, they must arrive at the same time. The photomultipliers used in each pixel introduce different delays which must be compensated to perform the additions properly. The effect of these delays has been analyzed, and a delay compensation system has been developed. The next trigger level consists of looking for simultaneous (or very near in time) triggers in neighbour telescopes. These function, together with others relating to interfacing different systems, have been developed in a system named Trigger Interface Board (TIB). This system is comprised of one module which will be placed inside the LSTs and MSTs cameras, and which will be connected to the neighbour telescopes through optical fibers. When a telescope receives a local trigger, it is resent to all the connected neighbours and vice-versa, so every telescope knows if its neighbours have been triggered. Once compensated the delay differences due to propagation in the optical fibers and in the air depending on the pointing direction, the TIB looks for coincidences, and in the case that the trigger condition is accomplished, the camera is read a fixed time after the local trigger arrived. Despite all the trigger system is the result of the cooperation of several groups, specially IFAE, Ciemat, ICC-UB and UCM in Spain, with some help from french and japanese groups, the Level 1 and the Trigger Interface Board constitute the core of this thesis, as they have been the two systems designed by the author of the thesis. For this reason, a large amount of technical information about these systems has been included. There are important future development lines regarding both the camera trigger (implementation in ASICS) and the stereo trigger (topological trigger), which will produce interesting improvements for the current designs during the following years, being useful for all the scientific community participating in CTA.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Policies trying to increase walking within urban mobility modal split usually highlight the importance of the functional patterns and the environmental quality of the urban space as major drivers of citizens modal choices. Functional characteristics would be mainly associated to an appropriate mix of land uses within neighbourhoods, whereas environmental quality would be associated to the characteristics of urban spaces. The purpose of this research is threefold: first, to identify relevant proxy indicators, which could characterize pedestrian-friendly land use mix and environmental quality. Second, to assess, for both traits, existing disparities among neighbourhoods in a major metropolitan area. And finally, to explore the association between both indicators and children mobility patterns: according to their built environment, which neighbourhoods have a greater proportion of children and, how is their mobility? Using data from the 2004 household mobility survey in the 128 neighbourhoods of the municipality of Madrid, this paper concludes that potentially favourable conditions at the neighbourhood level seem to have only a modest influence in,mobility patterns , in terms of both, selection of closer destinations and a higher share of walking within modal split. The city s policy choices, with intensive investment in road and public transport infrastructure may explain why short-distance mobility is not as important as it could have been expected in those neighbourhoods with more pedestrian-friendly conditions. The metropolitan transport system is providing mobility conditions, which make far-away destinations attractive to most citizens.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

The Spanish Ministry of Economy and Competitiveness is funding the SHERIF Research Project, which falls under the INNPACTO pr ogram. This project aims to increase the rate of the existing building refurbishment fro m the energy efficiency point of view by designing a facade system that must be an economica l, flexible and integrated solution 1 . Under this project has been performing several task s regarding the constructive characterization and energy evaluation of the therm al behaviour of facades on existing buildings . In order to perform the latter task, in which this article will focus, has been developing a survey of various buildings in the nei ghbourhood Ciudad de los Angeles, which has as main objective the comparison between the ac tual energy and light behaviour of different buildings, prior and posterior to any ref urbishment works have been undertaken. The evaluation of the actual performance of buildin gs before and after being refurbished is aimed to determine the impact of the work developed as well as learn from the work performed for future interventions.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Flat or worn wheels rolling on rough or corrugated tracks can provoke airborne noise and ground-borne vibration, which can be a serious concern for nearby neighbours of urban rail transit lines. Among the various treatments used to reduce vibration and noise, resilient wheels play an important role. In conventional resilient wheels, a slightly prestressed V­shaped rubber ring is mounted between the steel wheel centre and tyre. The elastic layer enhances rolling noise and vibration suppression, as well as impact reduction on the track. In this paper the effectiveness of resilient wheels in underground lines, in comparison to monobloc ones, is assessed. The analysed resilient wheel is able to carry greater loads than standard resilient wheels used for light vehicles. It also presents a greater radial resiliency and a higher axial stiffness than conventional V­wheels. The finite element method was used in this study. A quarter car model was defined, in which the wheelset was modelled as an elastic body. Several simulations were performed in order to assess the vibrational behaviour of elastic wheels, including modal, harmonic and random vibration analysis, the latter allowing the introduction of realistic vertical track irregularities, as well as the influence of the running speed. Due to numerical problems some simplifications were needed. Parametric variations were also performed, in which the sensitivity of the whole system to variations of rubber prestress and Poisson’s ratio of the elastic material was assessed.Results are presented in the frequency domain, showing a better performance of the resilient wheels for frequencies over 200 Hz. This result reveals the ability of the analyzed design to mitigate rolling noise, but not structural vibrations, which are primarily found in the lower frequency range.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

An actual case of an underground railway in the neighbourhood of habitation buildings has been analyzed. The study has been based on a twodimensional BEM model including a tunnel and a typical building. The soil properties were obtained using geophysical techniques. After a sensitivity study, the model has been simplyfied and validated by comparison with "in situ" measurements. Using this simplyfied model, a parametric study has been done including trenches and walls of different materials and different depths at two different distances from the tunnel. The reductions obtained with the different solutions can then be compared.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This contribution deals with the question, what makes cities sustainable and integrative, and suggests an approach for "liveable cities of tomorrow" designed to sustain mobility. The liveable city of tomorrow needs to meet both ecological and social requirements in an integrative approach. To design urban patterns appropriate or “sustainable mobility” based on a concept of mobility defined as the number of accessible destinations (different to that for “fossil mobility” defined as the ability to cover distances) is a key element of such an approach. Considering the limited reserves of fossil fuels and the long lifetime of the built structure, mobility needs to rely on modes independent of fossil fuels (public transport and pedestrians) to make it sustainable and the urban pattern needs to be developed appropriately for these modes. Crucial for the success of public transport is the location of buildings within the catchment area of stops. An attractive urban environment for pedestrians is characterised by short distances in a compact settlement with appropriate/qualified urban density and mixed land use as well as by attractive public space. This, complemented by an integrative urban development on the quarter level including neighbourhood management with a broad spectrum of activity areas (social infrastructure, integration of diverse social and ethnic groups, health promotion, community living, etc.), results in increased liveability. The role of information technology in this context is to support a sustainable use of the built structures by organisational instruments. Sustainable and liveable communities offer many benefits for health, safety and well-being of their inhabitants.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The famous plan for Toulouse-Le Mirail, by Candilis/Josic/Woods (1961), proposed a radical and hitherto new public space, the dalle, an elevated linear ?stem? that wove the whole urban intervention and concentrated all the commercial, social and cultural activity of the neighbourhood. However, the project is today stigmatized as a total social failure. The dalle has been demolished and a traditional commercial street has been implemented. Was demolition the sole alternative for Le Mirail?s future? This paper aims at identifying certain themes around the conception of the dalle, capable of informing today?s theory and practice in the design of new shopping/public-scapes. It reflects on both the most positive values of the project and on its naiveties and mistakes, conscious of the social unrest that aggrandized them. Ultimately, it calls for a deeper reflection on the urban proposals of the Modern Movement, beyond demolition as the only possible solution.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

El WCTR es un congreso de reconocido prestigio internacional en el ámbito de la investigación del transporte y aunque las actas publicadas están en formato digital y sin ISSN ni ISBN, lo consideramos lo suficientemente importante como para que se considere en los indicadores. Policies trying to increase walking within urban mobility modal split usually highlight the importance of the functional patterns and the environmental quality of the urban space as major drivers of citizens modal choices. Functional characteristics would be mainly associated to an appropriate mix of land uses within neighbourhoods, whereas environmental quality would be associated to the characteristics of urban spaces. The purpose of this research is threefold: first, to identify relevant proxy indicators, which could characterize pedestrian-friendly land use mix and environmental quality. Second, to assess, for both traits, existing disparities among neighbourhoods in a major metropolitan area. And finally, to explore the association between both indicators and children mobility patterns: according to their built environment, which neighbourhoods have a greater proportion of children and, how is their mobility? Using data from the 2004 household mobility survey in the 128 neighbourhoods of the municipality of Madrid, this paper concludes that potentially favourable conditions at the neighbourhood level seem to have only a modest influence in,mobility patterns , in terms of both, selection of closer destinations and a higher share of walking within modal split. The citys policy choices, with intensive investment in road and public transport infrastructure may explain why short-distance mobility is not as important as it could have been expected in those neighbourhoods with more pedestrian-friendly conditions. The metropolitan transport system is providing mobility conditions, which make far-away destinations attractive to most citizens.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Neighbourhood representation and scale used to measure the built environment have been treated in many ways. However, it is anything but clear what representation of neighbourhood is the most feasible in the existing literature. This paper presents an exhaustive analysis of built environment attributes through three spatial scales. For this purpose multiple data sources are integrated, and a set of 943 observations is analysed. This paper simultaneously analyses the influence of two methodological issues in the study of the relationship between built environment and travel behaviour: (1) detailed representation of neighbourhood by testing different spatial scales; (2) the influence of unobserved individual sensitivity to built environment attributes. The results show that different spatial scales of built environment attributes produce different results. Hence, it is important to produce local and regional transport measures, according to geographical scale. Additionally, the results show significant sensitivity to built environment attributes depending on place of residence. This effect, called residential sorting, acquires different magnitudes depending on the geographical scale used to measure the built environment attributes. Spatial scales risk to the stability of model results. Hence, transportation modellers and planners must take into account both effects of self-selection and spatial scales.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The third Training School of the Action took place in Vitoria-Gasteiz (Basque country, Spain) from 24th to 26th September 2014. Vitoria-Gateiz has experimented an important urban outgrowth in the last decade, mainly through the planning and development of two new neighborhoods, Zabalgana and Salburúa, situated at the eastern and western border of the city, by the Greenbelt. These new development are well-equipped and designed according to sustainability principles. Nevertheless, among the main problems they present is their over-dimensioned public space, which creates some areas lacking enough density and mix of uses. On the other hand it is very expensive for the municipality to maintain these public space with the high Vitorian urban standards for public space. The proposed solution for this problem is a strategy of "re-densification" through the insertion of new uses The debate has arisen about which are the most adequate uses to insert in order to get an increasing of urban vitality, specially considering that housing has reached its peak and that Vitoria-Gasteiz is well served with social and sport amenities. The main goal of the TS was to offer an opportunity for the reflection about how urban agriculture might be an optimal alternative for the re-qualifying of this over-dimensioned public space in the new neighbourhoods, especially considering it synergic potential as a tool for production, leisure and landscaping, including the possibility of energy crops within the limits of urban space. Continuity with rural and natural surrounding area through alternatives for urban fringe at the small scale is a relevant issue to be considered as well within the reflection. Taking Zabalgana neighbourhood as a practical field for experiment, the Training School is conceived as a practical and intensive design charrette to be held during a whole day after two days of local knowledge-deepening through field visits and presentations.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

El objetivo general de esta Tesis Doctoral fue evaluar nuevos sistemas de alojamiento y cría de conejos de granja, estudiando tanto parámetros comportamentales (experimento 1) como productivos y reproductivos (experimento 3). Además, se evaluaron diferentes técnicas de muestreo con el fin de optimizar el tiempo empleado para el estudio del comportamiento animal (experimento 2). En el experimento 1, se estudió el comportamiento de conejas alojadas en dos tipos de jaulas (TJ), convencionales vs. alternativas con una plataforma elevada, en distintos estados fisiológicos (EF), lactantes y gestantes. Se observó el comportamiento de 12 conejas reproductoras con grabaciones de una duración de 24 h continuas. Independientemente del EF y TJ, las conejas pasaron gran parte de su tiempo sobre el reposapatas (57,7 %, de media). Sin embargo, debido al uso de la plataforma (23,0% del tiempo, de media), las conejas lactantes permanecieron un 36,6 % menos de tiempo (P<0,001) sobre el reposapatas y las gestantes un 27,0% menos (P<0,001) sobre el enrejillado en jaulas alternativas que en convencionales. En las jaulas alternativas, las conejas podían adoptar la postura “levantada”, sin embargo ésta fue observada solamente en conejas gestantes una media de 4,6 veces al día. Las conejas bebieron con mas frecuencia en jaulas convencionales que en alternativas (24,6 vs 19,1 veces al día; P<0,05). Se observó una mayor duración y frecuencia del comportamiento “interactuando con compañeras” en conejas gestantes alojadas en jaulas convencionales (276 s/d y 4,6 veces/d; P<0,05). La frecuencia de “interactuando con gazapos” fue menor en jaulas alternativas que en convencionales (2,4 vs 8,6 veces al día; P<0,01). La hora del día afectó al comportamiento de las conejas, teniendo un comportamiento menos activo durante las horas centrales del día. Durante las horas de oscuridad, las conejas estuvieron más inquietas realizando comportamientos como ‘encabritarse’ o amamantar, coincidiendo éstos en el tiempo en el cual las conejas pasaron más tiempo en la plataforma. Las conejas utilizaron frecuentemente la plataforma, independientemente del estado fisiológico. En la fase de lactación, las conejas utilizaron la plataforma para huir de los intentos de mamar por parte de los gazapos cuando éstas no estaban receptivas. El uso de la plataforma puede dar lugar a problemas higiénicos debidos tanto por la acumulación de heces sobre ella como por la caída de heces y orina sobre los animales que están en la parte inferior. La ausencia de estereotipias por parte de las conejas tanto en jaulas alternativas como en convencionales no sugiere una falta de bienestar debida al sistema de alojamiento. En el experimento 2, se compararon distintos métodos de observación simplificada con respecto un método de referencia usando grabaciones continuas de 24 h para la evaluación del comportamiento de conejas en distintos estados fisiológicos (gestantes y lactantes) alojadas en dos tipos de jaulas (convencionales y alternativas). Se analizaron un total de 576 h de grabaciones continuas de 24 h en 12 conejas reproductoras al final del periodo de lactación y en las mismas conejas después del destete. Los comportamientos observados se clasificaron en tres categorías independientes (localización en la jaula, postura y comportamientos funcionales). Se utilizaron grabaciones continuas de 24 h como método de referencia para validar otros cuatro métodos de observación simplificados, utilizando grabaciones de distinta duración y frecuencia a lo largo del día. Métodos regulares: corto y largo con 2.4 y 8 h de observación respectivamente, y métodos irregulares: corto y largo con 6 y 8 h de observación, respectivamente. Como resultado, se observó que independientemente del sistema de alojamiento, el mejor método para reducir el tiempo de observación necesario para evaluar el comportamiento de conejas reproductoras depende del tipo de variable a estudiar y del estado fisiológico de las conejas. En gestantes, los métodos irregulares no fueron adecuados para estimar comportamientos de larga duración tales como tumbada, sentada, descansando y acicalándose. Sin embargo, en ambos estados fisiológicos, los métodos regulares fueron precisos para los comportamientos de los grupos localización y postura y para comportamientos funcionales de larga duración. Por otro lado, los coeficientes de variación de los comportamientos poco frecuentes realizados principalmente durante el periodo de oscuridad fueron muy altos, y el método irregular largo obtuvo los menores errores de estimación para éstos comportamientos. En el experimento 3, se estudió el efecto de un uso combinado de lactaciones largas (hasta 46 días) con jaulas alternativas sobre los parámetros productivos y reproductivos de 104 conejas y sus camadas durante cinco ciclos reproductivos. La mitad de las conejas fueron alojadas en jaulas polivalentes convencionales (39 cm x 100 cm x 30 cm) y la otra mitad en jaulas polivalentes alternativas (39 cm x 100 cm x 60 cm), con una plataforma elevada. Dentro de cada grupo de alojamiento, la mitad de las conejas se destetaron a 32 días y la otra mitad a 46 días tras el parto. Las lactaciones más largas afectaron negativamente al peso (P<0,001), contenido en grasa y energía (P<0,05) de las conejas al final del periodo de lactación, pero éste efecto disminuyó con el número de partos. La fertilidad, prolificidad y la mortalidad de las conejas no fue afectada por la duración de la lactación. El destete tardío dio lugar a un mayor tamaño y peso de la camada al final del periodo de crecimiento (8,9 y 11,3 %, respectivamente) y a un menor índice de conversión por jaula durante el todo el periodo experimental (13,5 %) con respecto al destete convencional (P<0,001). Éstos resultados fueron paralelos a la menor mortalidad global (12,6 vs 17,6 %; P<0,05) observada en gazapos con destete tardío. Las diferencias en los parámetros productivos con las distintas edades al destete sólo fueron observadas en los ciclos con peor estado sanitario (tercer y quinto ciclo), en los cuales el destete tardío redujo la mortalidad. El tipo de jaula no afectó al peso de la coneja, condición corporal, mortalidad, fertilidad ni tamaño de camada durante los cinco primeros ciclos reproductivos. Sin embargo, el peso de la camada y el índice de conversión a los 21 días de edad fueron 4,2% mayor (P<0,001) y 5,0% menor (P<0,005) en animales alojados en jaulas alternativas que en jaulas convencionales. A día 59 las jaulas alternativas dieron lugar a camadas más pesadas (P<0,01); sin embargo, éste efecto fue influenciado por la densidad alcanzada en cada ciclo, ya que cuando la densidad de los animales fue menor que 40kg/m2 (tercer y quinto ciclo), el efecto del tipo de jaula sobre el peso de la camada no fue significativo. De los resultados obtenidos se puede concluir que el uso combinado de lactaciones más largas y jaulas con mayor superficie disponible con una plataforma elevada podría ser una alternativa para mejorar el bienestar animal en determinadas situaciones productivas. ABSTRACT The general aim of this PhD Thesis was to evaluate new housing and husbandry systems of farmed rabbits, studying behavioral (experiment 1), productive and reproductive (experiment 3) parameters. Moreover, different sampling techniques were evaluated in order to optimize the assessment of rabbit behaviour (experiment 2). In experiment 1, the behaviour of rabbit does housed in two different types of cage (TC), conventional vs. alternative with an elevated platform, at different physiological stages (PS), lactation and gestation was to study. Behavioural observations were carried out on 12 commercial rabbit does using continuous 24 hour video recording. Independently of PS and TC, rabbit does spent most of their time on foot mats (57.7 %, as average). However, due to the use of platforms (23.0% of time, as average), lactating does spent 36.6% less time (P<0.001) on foot mats and gestating does spent 27.0% less (P<0.001) time on wire mesh in alternative cages than in conventional cages. Alternative cages allowed for standing posture but this behaviour was only observed in gestating does (4.6 times a day, as average). Frequency of drinking was higher in conventional than in alternative cages (24.6 vs. 19.1 times a day; P<0.05). Gestating does housed in conventional cages reached the highest duration and frequency of interacting with neighbours (276 s/d and 4.6 times/d; P<0.05). The frequency of interacting with kits was lower in alternative than in conventional cages (2.4 vs. 8.6 times a day; P<0.01). Does’ behaviour was influenced by hour of day, being less active at the midday hours. During dark hours rabbit does more frequently performed restless behaviour such as hyperactivity or nursing, matching the time at which rabbit does spent more time on the platform. The platform was frequently used by rabbit does, independent of their physiological state, and during late lactation phase, when mothers were not receptive to nursing, does housed in alternative cages used the platform as a mean to flee from kids trying to suckle. The use of the platform might lead to hygienic problems due to retained faeces on the platform and faeces and urine falling onto animals located in the lower part of the cage. Stereotypies were not observed in any housing system, therefore conventional cages do not suggest lack of animal welfare. In experiment 2, it was compared the results of different simplified sampling methods of behavioural data with respect to reference records of 24-h in order to assess rabbit does behaviours at different physiological stages (gestation and lactation) in animals housed in two types of cages (conventional and alternative). A total of 576 h of continuous video of 12 rabbit does at the end of lactation and on the same females after weaning were analysed. The behavioural observations were studied using three independent categories of classification (location in the cage, posture and functional behaviours). Continuous behavioural recordings of 24 h were considered as the reference method to validate another 4 sampling methods of data collection by aggregated video recordings of different frequency and duration (regular short and long methods with 2.4 and 8 h of observation respectively, and irregular short and long methods with 6 and 8 h of observation, respectively). The current results showed that, independently of housing system, the best method to reduce the total observation time required to assess rabbit does behaviour depends on the trait studied and physiological stage of does. In gestating does, irregular methods were not suitable to estimate behaviours of long duration such as lying, sitting, resting and grooming. However, in both physiological stages, regular methods were accurate for location behaviours, postures and functional behaviours of long duration. Instead, for the study of infrequent behaviours performed mainly during dark period, where coefficients of variation were high, the irregular long method led to the lowest mean estimation errors. In experiment 3, the effects of the combined use of long lactation periods (46 days) with alternative cages on the reproductive and growth performance of 104 rabbit does and their litters during five consecutive reproductive cycles were studied. Half of does were housed in conventional polyvalent cages (39 cm x 100 cm x 30 cm) and the other half in alternative polyvalent cages (39 cm x 100 cm x 60 cm), with a raised platform. Half of the rabbit does in each type of cages were weaned at 32 and the other half at 46 days after parturition. Longer lactations affected negatively to body weight (P<0.001), fat and energy content (P<0.05) of rabbit does at the end of the lactation period, but this effect decreased with the number of parturitions. Fertility, prolificacy and doe mortality were not affected by lactation length. Late weaning led to higher litter size (by 8.9 %) and litter weight (by 11.3 %) at the end of growing period and lower feed conversion ratio per cage during the overall experimental period (13.5 %) than standard weaning (P<0.001). These results were parallels to a lower mortality (12.6 vs 17.6 %; P<0.05) of young rabbit weaned later during the overall experimental period. Differences in performances at different weaning ages were only observed during cycles with worst health status (third and fifth cycles) in which late weaning decreased mortality. Type of cage did not affect doe body weight and body condition, mortality, fertility, prolificacy and litter size during the five firsts reproductive cycles. Nevertheless, at day 21 litter weight and feed conversion ratio were 4.2 % higher (P<0.001) and 5.0 % lower (P<0.005) in animals housed in alternative than in conventional cages. Alternative cages also led to heavier litters at 59 days (P<0.01); however, this effect was influenced by density reached in each cycle, as when the density of animals was lower than 40 kg/m2 (cycles three and five), the difference of litter weight between alternative and conventional cages was not significant. From the results obtained it can be concluded that the combined use of longer lactations and cages with higher available surface with a raised platform could be an alternative to improve animal welfare in some productive situations.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The urban microclimate plays an important role in building energy consumption and thermal comfort in outdoor spaces. Nowadays, cities need to increase energy efficiency, reduce pollutant emissions and mitigate the evident lack of sustainability. In light of this, attention has focused on the bioclimatic concepts use in the urban development. However, the speculative unsustainability of the growth model highlights the need to redirect the construction sector towards urban renovation using a bioclimatic approach. The public space plays a key role in improving the quality of today’s cities, especially in terms of providing places for citizens to meet and socialize in adequate thermal conditions. Thermal comfort affects perception of the environment, so microclimate conditions can be decisive for the success or failure of outdoor urban spaces and the activities held in them. For these reasons, the main focus of this work is on the definition of bioclimatic strategies for existing urban spaces, based on morpho-typological components, urban microclimate conditions and comfort requirements for all kinds of citizens. Two case studies were selected in Madrid, in a social housing neighbourhood constructed in the 1970s based on Rational Architecture style. Several renovation scenarios were performed using a computer simulation process based in ENVI-met and diverse microclimate conditions were compared. In addition, thermal comfort evaluation was carried out using the Universal Thermal Climate Index (UTCI) in order to investigate the relationship between microclimate conditions and thermal comfort perception. This paper introduces the microclimate computer simulation process as a valuable support for decision-making for neighbourhood renovation projects in order to provide new and better solutions according to the thermal quality of public spaces and reducing energy consumption by creating and selecting better microclimate areas.