Lipids and polycyclic aromatic hydrocarbons in bottom sediments from the Atlantic sector of the Southern Ocean

Distribution and composition of lipids and contents of alkanes and polycyclic aromatic hydrocarbons(PAHs) in bottom sediments of the Scotia and Weddell seas are discussed. Comparatively low concentrations of organic carbon (average 0.35%) and lipids (average 0.024%) result from rapid decomposition of organic matter in upper layers of the water column. Composition of alkanes indicates that lipids are of autochthonous origin, and stable concentrations of PAHs (average 25.8 ppb, sigma 15.3 ppb) indicate that they represent the background level for bottom sediments. Higher concentrations of PAHs in sediments near the King George Island (252.1 ppb) and different distributions of individual polyarenes are produced there by the heating systems of the Polish Antarctic Station.

Success possibilities of grid parity in particular cases in the new spanish regulatory framework

During the last 10 years the Spanish photovoltaic market has experienced one of the most important increases worldwide. The continuous raise on the price of the electricity in Spain, as in other European countries, USA and Japan, as well as the decrease of the cost of solar photovoltaic systems along this decade is opening a new way to reach grid parity point in some particular scenarios. A new Spanish legislation is being performed toward selfconsumption, and it is in this new context where the grid parity in a wide sense could be achieved. This work will study different cases in Spain, in order to determine whether grid parity would be possible along 2012. Keywords: grid parity, self-consumption, photovoltaic, net-metering

In-field assessment of batteries and PV modules in a large photovoltaic rural electrification programme

Assuring the sustainability of quality in photovoltaic rural electrification programmes involves enhancing the reliability of the components of solar home systems as well as the characterization of the overall programme cost structure. Batteries and photovoltaic modules have a great impact on both the reliability and the cost assessment, the battery being the weakest component of the solar home system and consequently the most expensive element of the programme. The photovoltaic module, despite being the most reliable component, has a significant impact cost-wise on the initial investment, even at current market prices. This paper focuses on the in-field testing of both batteries and photovoltaic modules working under real operating conditions within a sample of 41 solar home systems belonging to a large photovoltaic rural electrification programme with more than 13,000 installed photovoltaic systems. Different reliability parameters such as lifetime have been evaluated, taking into account different factors, for example energy consumption rates, or the manufacturing quality of batteries. A degradation model has been proposed relating both loss of capacity and time of operation. The user e solar home system binomial is also analysed in order to understand the meaning of battery lifetime in rural electrification.

Luciano Kulczewski, arquitecto: Eclecticismo y procesos modernizadores en el Chile de la primera mitad del siglo XX

Esta investigación tiene por fin poner en valor la obra del arquitecto chileno Luciano Kulczewski, profesional que cumplió un rol clave y distintivo en la primera mitad del siglo XX, considerado como un período crucial para el desarrollo de la arquitectura nacional, ya que es el momento en que se produce el advenimiento de la modernidad en el país. Si bien su figura goza de un gran reconocimiento, solamente una parte de su obra es (re)conocida por la historiografía nacional. Su labor en el libre ejercicio de la profesión, como asimismo los distintos cargos administrativos y políticos que desempeñó en su vida, hacían suponer un corpus más amplio, como finalmente se pudo constatar en este estudio. El amplio catastro documentado permitió fehacientemente identificar el rol y el significado que esta obra cumpliera en la transición que hizo posible dejar atrás los valores impuesto por el Academicismo, para incorporar los procesos de modernización en los distintos ámbitos de la arquitectura. Por tanto, el quehacer de Kulczewski se reveló como ejemplar y paradigmático. Una de las ilustraciones más elocuentes a este respecto fue la precursora realización de edificios en altura para uso residencial. Esta tipología lo obligó a trabajar con nuevos materiales y técnicas constructivas, junto a la necesidad de introducir las modernas tecnologías que estos portentos arquitectónicos requerían para su funcionamiento, como era el uso de ascensores y los sistemas de calefacción centralizada. El estudio del contexto urbano de sus obras permitió dar cuenta también de los procesos que estaban convirtiendo a las principales ciudades del país en urbes ‘modernas’. En este ámbito, destaca la nueva concepción urbanística que llegaba vinculada a los barrios-jardín, que contrariamente a lo establecido por el urbanismo tradicional, implicó inéditas maneras de articular la ciudad y el empleo de nuevas tipologías residenciales. Estas concepciones de ciudad encontraron eco principalmente en las urbanizaciones que se estaban realizando en las nuevas comunas de la capital, contexto elegido por el arquitecto para llevar a cabo algunos innovadores conjuntos habitacionales, hoy considerados modélicos, y que estaban destinados a un nuevo estrato social empoderado y demandante: la clase media. Su particular preocupación por las cuestiones sociales, las que entraron en crisis con el devenir del siglo XX, lo llevaron a desarrollar una activa vida política, que culminó con un importante puesto administrativo en el primer Gobierno Radical que tuvo lugar en el país. Desde esa posición, pudo gestionar y dar solución apropiada a la urgente necesidad de viviendas obreras que requería el país, creando los primeros edificios colectivos destinados a este grupo social. Esto a la vez supuso un acercamiento más sustancial a las nuevas propuestas vinculadas al Movimiento Moderno. En conclusión, su quehacer hizo eco de los estilos vanguardistas y modernos que arribaron provenientes de Europa, pero reconociendo las realidades propias del país, de tal forma que la apropiación, y no la reproducción, fue su sello. En este proceso de adecuación al medio local, los modelos foráneos se desprenderán de muchas de sus principios rectores originales, lo que sumado a la impronta de un imaginario propio y original, convierten a sus creaciones en un caso singular en el contexto del la arquitectura chilena. ABSTRACT This research aims to add value to the work of Chilean architect Luciano Kulczewski, a professional who accomplished a key and distinctive role in the first half of the twentieth century, which is considered as a crucial period for the development of the Chilean architecture, since it corresponds to the arrive of Modernity in this country. While his figure is widely recognized, only a portion of his oeuvre is known (or acknowledged) by national historiography. Because of his work as a freelance professional and another administrative and political position he held in his life, it is possible to assume a larger corpus, as it was finally confirmed by this study. The copious documented cadastre allowed convincingly to identify the role and significance that this work fulfilled in the transition that made possible leaving behind the values imposed by Academicism, and thus to incorporate the modernization processes in the different fields of architecture. Therefore, the work of Kulczewski revealed itself as exemplary and paradigmatic. One of the most eloquent illustrations to this regard was the pioneering construction of high-rise buildings with a residential purpose. This typology drove him to work with new materials and constructive techniques, alongside with the need of introducing new modern technologies required by these architectonical advances for its operations, like the use of elevators and central heating systems. The study of the urban context of his work allowed also accounting the processes the major cities of the country went through in order to become 'modern' cities. In this context, it stands out the new urban conception linked to the idea of garden city, which was contrary to the practices of the traditional urbanism, and that implied new ways of articulating the city and that the use of new residential typologies. These urban notions were mainly echoed in the urbanizations that were made in the new districts of the city, scenario chosen by the architect for the concretion of innovative housing projects, nowadays thought as paradigmatic, and that were oriented for a new empowered and demanding social group: the middle class. His particular concern for social issues, which ones came into crisis with the arrival of the twentieth century, led him to take an active political role, culminating with an important administrative position in the first Radical Government that took place in the country. From that position, he could manage and provide adequate solutions to the urgent worker’s housing needs that required the country, creating the first collective buildings for this social group. This supposed a more substantial approach to new proposals of the Modern Movement. To conclude, his oeuvre was influenced by the avant-garde and modern styles that arrived from Europe, but with the proper adjustments to the local requirements, so that it is possible to say that appropriation more than reproduction was his hallmark. In this process, these features were transformed in order to get more flexibility for their adaptation to the Chilean needs that added to a personal and peculiar imaginary, which transformed his works into a unique case in the national architecture history.

Diseño acústico y electroacústico de Waipahu Transit Center en Honolulú, Hawái

El objetivo de este Proyecto Fin de Grado es el diseño de megafonía y PAGA (Public Address /General Alarm) de la estación de tren Waipahu Transit Center en la ciudad de Honolulú, Hawái. Esta estación forma parte de una nueva línea de tren que está en proceso de construcción actualmente llamada Honolulu Rail Transit. Inicialmente la línea de tren constará de 21 estaciones, en las que prácticamente todas están diseñadas como pasos elevados usando como referencia las autopistas que cruzan la isla. Se tiene prevista su fecha de finalización en el año 2019, aunque las primeras estaciones se inaugurarán en 2017. Se trata en primer lugar un estudio acústico del recinto a sonorizar, eligiendo los equipos necesarios: conmutadores, altavoces, amplificadores, procesador, equipo de control y micrófonos. Este primer estudio sirve para obtener una aproximación de equipos necesarios, así como la posible situación de estos dentro de la estación. Tras esto, se procede a la simulación de la estación mediante el programa de simulación acústica y electroacústica EASE 4.4. Para ello, se diseña la estación en un modelo 3D, en el que cada superficie se asocia a su material correspondiente. Para facilitar el diseño y el cómputo de las simulaciones se divide la estación en 3 partes por separado. Cada una corresponde a un nivel de la estación: Ground level, el nivel inferior que contiene la entrada; Concourse Level, pasillo que comunica los dos andenes; y Platform Level, en el que realizarán las paradas los trenes. Una vez realizado el diseño se procede al posicionamiento de altavoces en los diferentes niveles de la estación. Debido al clima existente en la isla, el cual ronda los 20°C a lo largo de todo el año, no es necesaria la instalación de sistemas de aire acondicionado o calefacción, por lo que la estación no está totalmente cerrada. Esto supone un problema al realizar las simulaciones en EASE, ya que al tratarse de un recinto abierto se deberán hallar parámetros como el tiempo de reverberación o el volumen equivalente por otros medios. Para ello, se utilizará el método Ray Tracing, mediante el cual se halla el tiempo de reverberación por la respuesta al impulso de la sala; y a continuación se calcula un volumen equivalente del recinto mediante la fórmula de Eyring. Con estos datos, se puede proceder a calcular los parámetros necesarios: nivel de presión sonora directo, nivel de presión sonora total y STI (Speech Transmission Index). Para obtener este último será necesario ecualizar antes en cada uno de los niveles de la estación. Una vez hechas las simulaciones, se comprueba que el nivel de presión sonora y los valores de inteligibilidad son acordes con los requisitos dados por el cliente. Tras esto, se procede a realizar los bucles de altavoces y el cálculo de amplificadores necesarios. Se estudia la situación de los micrófonos, que servirán para poder variar la potencia emitida por los altavoces dependiendo del nivel de ruido en la estación. Una vez obtenidos todos los equipos necesarios en la estación, se hace el conexionado entre éstos, tanto de una forma simplificada en la que se pueden ver los bucles de altavoces en cada nivel de la estación, como de una forma más detallada en la que se muestran las conexiones entre cada equipo del rack. Finalmente, se realiza el etiquetado de los equipos y un presupuesto estimado con los costes del diseño del sistema PAGA. ABSTRACT. The aim of this Final Degree Project is the design of the PAGA (Public Address / General Alarm) system in the train station Waipahu Transit Center in the city of Honolulu, Hawaii. This station is part of a new rail line that is currently under construction, called Honolulu Rail Transit. Initially, the rail line will have 21 stations, in which almost all are designed elevated using the highways that cross the island as reference. At first, it is treated an acoustic study in the areas to cover, choosing the equipment needed: switches, loudspeakers, amplifiers, DPS, control station and microphones. This first study helps to obtain an approximation of the equipments needed, as well as their placement inside the station. Thereafter, it is proceeded to do the simulation of the station through the acoustics and electroacoustics simulation software EASE 4.4. In order to do that, it is made the 3D design of the station, in which each surface is associated with its material. In order to ease the design and calculation of the simulations, the station has been divided in 3 zones. Each one corresponds with one level of the station: Ground Level, the lower level that has the entrance; Concourse Level, a corridor that links the two platforms; and Platform Level, where the trains will stop. Once the design is made, it is proceeded to place the speakers in the different levels of the station. Due to the weather in the island, which is about 20°C throughout the year, it is not necessary the installation of air conditioning or heating systems, so the station is not totally closed. This cause a problem when making the simulations in EASE, as the project is open, and it will be necessary to calculate parameters like the reverberation time or the equivalent volume by other methods. In order to do that, it will be used the Ray Tracing method, by which the reverberation time is calculated by the impulse response; and then it is calculated the equivalent volume of the area with the Eyring equation. With this information, it can be proceeded to calculate the parameters needed: direct sound pressure level, total sound pressure level and STI (Speech Transmission Index). In order to obtain the STI, it will be needed to equalize before in each of the station’s levels. Once the simulations are done, it is checked that the sound pressure level and the intelligibility values agree with the requirements given by the client. After that, it is proceeded to perform the speaker’s loops and the calculation of the amplifiers needed. It is studied the placement of the microphones, which will help to vary the power emitted by the speakers depending on the background noise level in the station. Once obtained all the necessary equipment in the station, it is done the connection diagram, both a simplified diagram in which there can be seen the speaker’s loops in each level of the station, or a more detailed diagram in which it is shown the wiring between each equipment of the rack. At last, it is done the labeling of the equipments and an estimated budget with the expenses for the PAGA design.

Islanding detection in Microgrids using Harmonic Signature

In recent years, there has been a growing interest in incorporating microgrids in electrical power networks. This is due to various advantages they present, particularly the possibility of working in either autonomous mode or grid connected, which makes them highly versatile structures for incorporating intermittent generation and energy storage. However, they pose safety issues in being able to support a local island in case of utility disconnection. Thus, in the event of an unintentional island situation, they should be able to detect the loss of mains and disconnect for self-protection and safety reasons. Most of the anti-islanding schemes are implemented within control of single generation devices, such as dc-ac inverters used with solar electric systems being incompatible with the concept of microgrids due to the variety and multiplicity of sources within the microgrid. In this paper, a passive islanding detection method based on the change of the 5th harmonic voltage magnitude at the point of common coupling between grid-connected and islanded modes of operation is presented. Hardware test results from the application of this approach to a laboratory scale microgrid are shown. The experimental results demonstrate the validity of the proposed method, in meeting the requirements of IEEE 1547 standards.

Aportación de la monitorización mediante redes de sensores y técnicas no invasivas para la conservación preventiva del Patrimonio

La presente tesis doctoral presenta una serie de estudios en el campo del patrimonio basados en metodologías de monitorización mediante redes de sensores y técnicas no invasivas con el objetivo de realizar nuevas aportaciones a la conservación preventiva mediante el seguimiento de los daños de deterioro o la prevención de los mismos. Las metodologías de monitorización mediante el despliegue de redes tridimensionales basadas en data loggers abordan estudios microclimáticos, de confort y energéticos a corto plazo, donde se establecen conclusiones relativas a la eficiencia energética de tres sistemas de calefacción muy utilizados en iglesias de la región centro de la Península Ibérica, abordando aspectos de afección de los mismos en el confort de los ocupantes o en el deterioro de los elementos patrimoniales o constructivos. Se desplegaron además distintas plataformas de redes de sensores inalámbricas procediendo a analizar en esta tesis cuál es la que presenta mejores resultados en el ámbito del patrimonio con el objetivo de una monitorización a largo plazo y considerando aspectos de comunicaciones, consumo y configuración de las redes. Una vez conocida la plataforma que presenta mejores resultados comparativos se muestra una metodología de estudio de la calidad de las comunicaciones en múltiples escenarios de patrimonio cultural y natural con la misma, que servirá para establecer una serie de aspectos a considerar en el despliegue de redes de sensores inalámbricas en futuros escenarios a monitorizar. Al igual que ocurre con las redes de sensores basadas en data loggers, las tareas de monitorización desarrolladas en esta tesis mediante el despliegue de las distintas plataformas inalámbricas ha permitido la detección de numerosos fenómenos de deterioro que son descritos a lo largo de la investigación y cuyo seguimiento supone una aportación a la prevención de daños en los distintos escenarios. Asimismo en el desarrollo de la tesis se realiza una aportación para la conservación preventiva mediante la monitorización con distintas técnicas no invasivas como la termografía infrarroja, las medidas de humedad superficial mediante protimeter, las técnicas de prospección de resistividad eléctrica de alta resolución o la prospección georradar. De este modo se desarrollan distintas aportaciones y conclusiones acerca de las ventajas y/o limitaciones de uso de las mismas analizando la idoneidad de aplicar cada una de ellas en distintas fases de análisis o con distintas capacidades de detección o caracterización de los daños. El estudio de imbricación de dichas técnicas ha sido desarrollado en un escenario real que presenta graves daños por humedad, habiendo sido posible la caracterización del origen de los mismos. ABSTRACT This doctoral dissertation discusses field research conducted to monitor heritage assets with sensor networks and other non-invasive techniques. The aim pursued was to contribute to conservation by tracking or preventing decay-induced damage. Monitoring methodologies based on three-dimensional data logger networks were used in short-term micro-climatic, comfort and energy studies to draw conclusions about the energy efficiency of three heating systems widely used in central Iberian churches. The impact of these systems on occupant comfort and decay of heritage or built elements was also explored. Different wireless sensor platforms were deployed and analysed to determine which delivered the best results in the context of long-term heritage monitoring from the standpoints of communications, energy demand and network architecture. A methodology was subsequently designed to study communication quality in a number of cultural and natural heritage scenarios and help establish the considerations to be borne in mind when deploying wireless sensor networks for heritage monitoring in future. As in data logger-based sensor networks, the monitoring conducted in this research with wireless platforms identified many instances of decay, described hereunder. Tracking those situations will help prevent damage in the respective scenarios. The research also contributes to preventive conservation based on non-invasive monitoring using techniques such as infrared thermography, protimeter-based surface damp measurements, high resolution electrical resistivity surveys and georadar analysis. The conclusions drawn address the advantages and drawbacks of each technique and its suitability for the various phases of analysis and capacity to detect or characterise damage. This dissertation also describes the intermeshed usage of these techniques that led to the identification of the origin of severe damp-induced damage in a real scenario.

Characterisation of the operation & maintenance phase in PV rural electrification programmes

Con 1.300 millones de personas en el mundo sin acceso a la electricidad (la mayoría en entornos rurales de países empobrecidos), la energía solar fotovoltaica constituye una solución viable técnica y económicamente para electrificar las zonas más remotas del planeta donde las redes eléctricas convencionales no llegan. Casi todos los países en el mundo han desarrollado algún tipo de programa de electrificación fotovoltaica rural durante los últimos 40 años, principalmente los países más pobres, donde a través de diferentes modelos de financiación, se han instalado millones de sistemas solares domiciliarios (pequeños sistemas fotovoltaicos para uso doméstico). Durante este largo período, se han ido superando muchas barreras, como la mejora de la calidad de los sistemas fotovoltaicos, la reducción de costes, la optimización del diseño y del dimensionado de los sistemas, la disponibilidad financiera para implantar programas de electrificación rural, etc. Gracias a esto, la electrificación rural descentralizada ha experimentado recientemente un salto de escala caracterizada por la implantación de grandes programas con miles de sistemas solares domiciliarios e integrando largos períodos de mantenimiento. Muchos de estos grandes programas se están llevando a cabo con limitado éxito, ya que generalmente parten de supuestos e hipótesis poco contrastadas con la realidad, comprometiendo así un retorno económico que permita el desarrollo de esta actividad a largo plazo. En este escenario surge un nuevo reto: el de cómo garantizar la sostenibilidad de los grandes programas de electrificación rural fotovoltaica. Se argumenta que la principal causa de esta falta de rentabilidad es el imprevisto alto coste de la fase de operación y mantenimiento. Cuestiones clave tales como la estructura de costes de operación y mantenimiento o la fiabilidad de los componentes del sistema fotovoltaico no están bien caracterizados hoy en día. Esta situación limita la capacidad de diseñar estructuras de mantenimiento capaces de asegurar la sostenibilidad y la rentabilidad del servicio de operación y mantenimiento en estos programas. Esta tesis doctoral tiene como objetivo responder a estas cuestiones. Se ha realizado varios estudios sobre la base de un gran programa de electrificación rural fotovoltaica real llevado a cabo en Marruecos con más de 13.000 sistemas solares domiciliarios instalados. Sobre la base de este programa se ha hecho una evaluación en profundidad de la fiabilidad de los sistemas solares a partir de los datos de mantenimiento recogidos durante 5 años con más de 80.000 inputs. Los resultados han permitido establecer las funciones de fiabilidad de los equipos tal y como se comportan en condiciones reales de operación, las tasas de fallos y los tiempos medios hasta el fallo para los principales componentes del sistema, siendo este el primer caso de divulgación de resultados de este tipo en el campo de la electrificación rural fotovoltaica. Los dos principales componentes del sistema solar domiciliario, la batería y el módulo fotovoltaico, han sido analizados en campo a través de una muestra de 41 sistemas trabajando en condiciones reales pertenecientes al programa solar marroquí. Por un lado se ha estudiado la degradación de la capacidad de las baterías y por otro la degradación de potencia de los módulos fotovoltaicos. En el caso de las baterías, los resultados nos han permitido caracterizar la curva de degradación en capacidad llegando a obtener una propuesta de nueva definición del umbral de vida útil de las baterías en electrificación rural. También sobre la base del programa solar de Marruecos se ha llevado a cabo un estudio de caracterización de los costes reales de operación y mantenimiento a partir de la base de datos de contabilidad del programa registrados durante 5 años. Los resultados del estudio han permitido definir cuáles son costes que más incidencia tienen en el coste global. Se han obtenido los costes unitarios por sistema instalado y se han calculado los montantes de las cuotas de mantenimiento de los usuarios para garantizar la rentabilidad de la operación y mantenimiento. Finalmente, se propone un modelo de optimización matemática para diseñar estructuras de mantenimiento basado en los resultados de los estudios anteriores. La herramienta, elaborada mediante programación lineal entera mixta, se ha aplicado al programa marroquí con el fin de validar el modelo propuesto. ABSTRACT With 1,300 million people worldwide deprived of access to electricity (mostly in rural environments), photovoltaic solar energy has proven to be a cost‐effective solution and the only hope for electrifying the most remote inhabitants of the planet, where conventional electric grids do not reach because they are unaffordable. Almost all countries in the world have had some kind of rural photovoltaic electrification programme during the past 40 years, mainly the poorer countries, where through different organizational models, millions of solar home systems (small photovoltaic systems for domestic use) have been installed. During this long period, many barriers have been overcome, such as quality enhancement, cost reduction, the optimization of designing and sizing, financial availability, etc. Thanks to this, decentralized rural electrification has recently experienced a change of scale characterized by new programmes with thousands of solar home systems and long maintenance periods. Many of these large programmes are being developed with limited success, as they have generally been based on assumptions that do not correspond to reality, compromising the economic return that allows long term activity. In this scenario a new challenge emerges, which approaches the sustainability of large programmes. It is argued that the main cause of unprofitability is the unexpected high cost of the operation and maintenance of the solar systems. In fact, the lack of a paradigm in decentralized rural services has led to many private companies to carry out decentralized electrification programmes blindly. Issues such as the operation and maintenance cost structure or the reliability of the solar home system components have still not been characterized. This situation does not allow optimized maintenance structure to be designed to assure the sustainability and profitability of the operation and maintenance service. This PhD thesis aims to respond to these needs. Several studies have been carried out based on a real and large photovoltaic rural electrification programme carried out in Morocco with more than 13,000 solar home systems. An in‐depth reliability assessment has been made from a 5‐year maintenance database with more than 80,000 maintenance inputs. The results have allowed us to establish the real reliability functions, the failure rate and the main time to failure of the main components of the system, reporting these findings for the first time in the field of rural electrification. Both in‐field experiments on the capacity degradation of batteries and power degradation of photovoltaic modules have been carried out. During the experiments both samples of batteries and modules were operating under real conditions integrated into the solar home systems of the Moroccan programme. In the case of the batteries, the results have enabled us to obtain a proposal of definition of death of batteries in rural electrification. A cost assessment of the Moroccan experience based on a 5‐year accounting database has been carried out to characterize the cost structure of the programme. The results have allowed the major costs of the photovoltaic electrification to be defined. The overall cost ratio per installed system has been calculated together with the necessary fees that users would have to pay to make the operation and maintenance affordable. Finally, a mathematical optimization model has been proposed to design maintenance structures based on the previous study results. The tool has been applied to the Moroccan programme with the aim of validating the model.

Arsenic, antimony and selenium in urban soils: potential risks for human health in urban gardening

The benefits of urban agriculture are many and well documented, ranging from health improvement to community betterment, more sustainable urban development and environment protection. On the negative side, urban soils are commonly enriched in toxic trace elements that have accumulated over time through the deposition of atmospheric particles (generated by automotive traffic, heating systems, historical industrial activities and resuspended street dust), and the uncontrolled disposal of domestic, commercial and industrial wastes. This in turn has given rise to concerns about the level of exposure of urban farmers to these elements and the potential health hazards associated with this exposure. Research efforts in this field have started relatively recently and have almost systematically omitted the influence of Sb and Se, and to a lesser extent of As, although all three have proven toxic effects.

A comparative study of four passive building energy simulations : DOE-2.1, BLAST SUNCAT-2.4, DEROB-III /

"Work Performed Under Contract No. EG-77-C-01-4042."

The structure of building specifications /

Includes bibliographical references (p. 76-77).

Gas-fired radiant heaters

This dissertation covers four areas of particular interest for the successful application of radiant heating in industrial environments. In it the author tackles the problem of how to predict the thermal comfort produced both by single heaters and also systems of heaters; proposes a method for modelling the mechanisms by which heaters interact with the buildings in which they are installed, in the static and dynamic cases; explores techniques for measuring the radiation produced by heaters; and presents experiments concerned with finding the temperatures and power balances prevailing during normal operation. It is contended that, whilst the generally accepted guides for sizing and operating space heating plant were a good first approximation, there are intrinsic subtleties arising from the fact that the primary mode of heat transfer in this instance is radiative. These nuances are concerned with how best to maximise the heat transfer from the heat source to the heated object; the placement of heaters within a system; and an assessment of the various techniques and strategies involved in controlling a radiant heating system. The conclusions reached are that: if sized and controlled correctly radiant heating systems offer considerable operational advantages over other types of space heating systems in certain applications, in terms of both economy and controllability. The efficacy of radiant heating systems is affected primarily by the control strategy implemented; secondarily, by the structure of the building into which it is installed; and only marginally by all other factors.

Alkenone unsaturation index and alkenones in ODP Hole 161-977A

A number of essential elements closely related to each other are involved in the Earth's climatic system. The temporal and spatial distribution of insolation determines wind patterns and the ocean's thermohaline pump. In turn, these last two are directly linked to the extension and retreat of marine and continental ice and to the chemistry of the atmosphere and the ocean. The variability of these elements may trigger, amplify, sustain or globalize rapid climatic changes. Paleoclimatic oscillations have been identified in this thesis by using fossil organic compounds synthesized by marine and terrestrial flora. High sedimentation rate deposits at the Barents and the Iberian peninsula continental margins were chosen in order to estimate the climatic changes on centennial time resolution. At the Barents margin, the sediment recovered was up to 15,000 years old (unit ''a'', from latin ''annos'') (M23258; west of the Bjørnøya island). At the Iberian margin, the sediment cores studied covered a wide range of time spans: up to 115,000 a (MD99-2343; north of the Minorca island), up to 250,000 a (ODP-977A; Alboran basin) and up to 420,000 a (MD01-2442, MD01-2443, MD01-2444, MD01-2445; close to the Tagus abyssal plain). At the northern site, inputs containing marine, continental and ancient reworked organic matter provided a detailed reconstruction of climate history at the time of the final retreat of the Barents ice sheet. At the western Barents continental slope, warm climatic conditions were observed during the early Holocene (~from 8,650 a to 5,240 a ago); in contrast, an apparent long-term cooling trend occurred in the late Holocene (~from 5,240 a to 760 a ago), in consistence with other paleoarchives from northern and southern European latitudes. The Iberian margin sites, which were never covered with large ice sheets, preserved exceptionally complete sequences of rapid events during ice ages hitherto not studied in such great detail: during the last glacial (~from 70,900 a to 11,800 a ago), the second glacial (~from 189,300 a to 127,500 a ago), the third ice age (~from 278,600 a to 244,800 a ago) and the fourth (~from 376,300 a to 337,500 a ago). In this thesis, crucial research questions were brought up concerning the severity of different glacial periods, the intensity and rates of the recorded oscillations and the long distance connections related to rapid climate change. The data obtained provide a sound basis to further research on the mechanisms involved in this rapid climate variability. An essential point of the research was the evidence that, over the past 420,000 a, at the whole Iberian margin, warm and stable long periods similar to the Holocene always ended abruptly in few centuries after a gradual deterioration of climate conditions. The detailed estimate of past climate variability provides clues to the natural end of the present warm period. Returning to an ice age in European lands would be exacerbated by a number of factors: a lack of differential solar heating between northern and southern north Atlantic latitudes, enhanced evaporation at low latitudes, and an increase in snowfall or iceberg discharges at northern regions. It must be emphasized that all climatic oscillations observed in this thesis were caused by forces of nature, i.e. the last two centuries were not taken into consideration.