Polyolefin fibre-reinforced concrete : from material behaviour to numerical and design considerations

La presente Tesis proporciona una gran cantidad de informaci��n con respecto al uso de un nuevo y avanzado material polim��rico (con base de poliolefina) especialmente adecuada para ser usada en forma de fibras como adici��n en el hormig��n. Se han empleado fibras de aproximadamente 1 mm de di��metro, longitudes entre 48 y 60 mm y una superficie corrugada. Las prometedoras propiedades de este material (baja densidad, bajo coste, buen comportamiento resistente y gran estabilidad qu��mica) justifican el inter��s en desarrollar el esfuerzo de investigaci��n requerido para demostrar las ventajas de su uso en aplicaciones pr��cticas. La mayor parte de la investigaci��n se ha realizado usando hormig��n autocompactante como matriz, ya que este material es ��ptimo para el relleno de los encofrados del hormig��n, aunque tambi��n se ha empleado hormig��n normal vibrado con el fin de comparar algunas propiedades. Adem��s, el importante desarrollo del hormig��n reforzado con fibras en los ��ltimos a��os, tanto en investigaci��n como en aplicaciones pr��cticas, tambi��n es muestra del gran inter��s que los resultados y consideraciones de dise��o que esta Tesis pueden tener. El material compuesto resultante, Hormig��n Reforzado con Fibras de Poliolefina (HRFP o PFRC por sus siglas inglesas) ha sido exhaustivamente ensayado y estudiado en muchos aspectos. Los resultados permiten establecer c��mo conseguidos los objetivos buscados: -Se han cuantificado las propiedades mec��nicas del PFRC con el fin de demostrar su buen comportamiento en la fase fisurada de elementos estructurales sometidos a tensiones de tracci��n. -Contrastar los resultados obtenidos con las bases propuestas en la normativa existente y evaluar las posibilidades para el uso del PFRC con fin estructural para sustituir el armado tradicional con barras de acero corrugado para determinadas aplicaciones. -Se han desarrollado herramientas de c��lculo con el fin de evaluar la capacidad del PFRC para sustituir al hormig��n armado con las barras habituales de acero. -En base a la gran cantidad de ensayos experimentales y a alguna aplicaci��n real en la construcci��n, se han podido establecer recomendaciones y consejos de dise��o para que elementos de este material puedan ser proyectados y construidos con total fiabilidad. Se presentan, adem��s, resultados prometedores en una nueva l��nea de trabajo en el campo del hormig��n reforzado con fibras combinando dos tipolog��as de fibras. Se combinaron fibras de poliolefina con fibras de acero como refuerzo del mismo hormig��n autocompactante detect��ndose sinergias que podr��an ser la base del uso futuro de esta tecnolog��a de hormig��n. This thesis provides a significant amount of information on the use of a new advanced polymer (polyolefin-based) especially suitable in the form of fibres to be added to concrete. At the time of writing, there is a noteworthy lack of research and knowledge about use as a randomly distributed element to reinforce concrete. Fibres with an approximate 1 mm diameter, length of 48-60 mm, an embossed surface and improved mechanical properties are employed. The promising properties of the polyolefin material (low density, inexpensive, and with good strength behaviour and high chemical stability) justify the research effort involved and demonstrate the advantages for practical purposes. While most of the research has used self-compacting concrete, given that this type of matrix material is optimum in filling the concrete formwork, for comparison purposes standard vibration compacted mixes have also been used. In addition, the interest in fibre-reinforced concrete technology, in both research and application, support the significant interest in the results and considerations provided by the thesis. The resulting composite material, polyolefin fibre reinforced concrete (PFRC) has been extensively tested and studied. The results have allowed the following objectives to be met: -Assessment of the mechanical properties of PFRC in order to demonstrate the good performance in the post-cracking strength for structural elements subjected to tensile stresses. -- Assessment of the results in contrast with the existing structural codes, regulations and test methods. The evaluation of the potential of PFRC to meet the requirements and replace traditional steel-bar reinforcement applications. -Development of numerical tools designed to evaluate the capability of PFRC to substitute, either partially or totally, standard steel reinforcing bars either alone or in conjunction with steel fibres. -Provision, based on the large amount of experimental work and real applications, of a series of guidelines and recommendations for the practical and reliable design and use of PFRC. Furthermore, the thesis also reports promising results about an innovative line in the field of fibre-reinforced concrete: the design of a fibre cocktail to reinforce the concrete by using two types of fibres simultaneously. Polyolefin fibres were combined with steel fibres in self-compacting concrete, identifying synergies that could serve as the base in the future use of fibre-reinforced concrete technology.

The usefulness of Usability and User Experience evaluation methods on an e-Learning platform development from a developer's perspective: A case study

The development of a web platform is a complex and interdisciplinary task, where people with different roles such as project manager, designer or developer participate. Different usability and User Experience evaluation methods can be used in each stage of the development life cycle, but not all of them have the same influence in the software development and in the final product or system. This article presents the study of the impact of these methods applied in the context of an e-Learning platform development. The results show that the impact has been strong from a developer's perspective. Developer team members considered that usability and User Experience evaluation allowed them mainly to identify design mistakes, improve the platform's usability and understand the end users and their needs in a better way. Interviews with potential users, clickmaps and scrollmaps were rated as the most useful methods. Finally, these methods were considered unanimously very useful in the context of the entire software development, only comparable to SCRUM meetings and overcoming the rest of involved factors.

Differences brick facade design to horizontal loads between the Spanish and European standards

Brick facades are a construction type, strongly linked to local construction characteristics and methods. In Spain, particularly in Castilla, the facades have been built since the '80s with Castilian half foot (11.5 cm), resting on the edge of slabs. The design of these facades, to horizontal loads from wind, depending on the codes used, can lead to completely different valid solutions. Applying same loads, the facades studied with current European standard (Eurocode 6), have a maximum length of 7.1 m between supports, while the Spanish code, Technical Building Code - Structural Safety Masonry, (CTE SE-F), 8.4 m can be achieved. This represents an increase of flexural strength, depending on the calculation model used, which can reach until 8 times. This is due to the difference of the calculation method and the structural model in one and another standard, depending on if this facade is analyzed as a vertical or horizontal beam or by formation of a vertical or horizontal archh. This paper analyzes the constructive solution of the brick facades that results from applying Spanish or European standards and how it affects the model applied in the safety of the resulting facade.

Color uniformity in spotligths - visual perception and system design

La iluminaci��n con diodos emisores de luz (LED) est�� reemplazando cada vez en mayor medida a las fuentes de luz tradicionales. La iluminaci��n LED ofrece ventajas en eficiencia, consumo de energ��a, dise��o, tama��o y calidad de la luz. Durante m��s de 50 a��os, los investigadores han estado trabajando en mejoras LED. Su principal relevancia para la iluminaci��n est�� aumentando r��pidamente. Esta tesis se centra en un campo de aplicaci��n importante, como son los focos. Se utilizan para enfocar la luz en ��reas definidas, en objetos sobresalientes en condiciones profesionales. Esta iluminaci��n de alto rendimiento requiere una calidad de luz definida, que incluya temperaturas ajustables de color correlacionadas (CCT), de alto ��ndice de reproducci��n crom��tica (CRI), altas eficiencias, y colores vivos y brillantes. En el paquete LED varios chips de diferentes colores (rojo, azul, f��sforo convertido) se combinan para cumplir con la distribuci��n de energ��a espectral con alto CRI. Para colimar la luz en los puntos concretos deseados con un ��ngulo de emisi��n determinado, se utilizan blancos sintonizables y diversos colores de luz y ��pticas secundarias. La combinaci��n de una fuente LED de varios colores con elementos ��pticos puede causar falta de homogeneidad crom��tica en la distribuci��n espacial y angular de la luz, que debe resolverse en el dise��o ��ptico. Sin embargo, no hay necesidad de uniformidad perfecta en el punto de luz debido al umbral en la percepci��n visual del ojo humano. Por lo tanto, se requiere una descripci��n matem��tica del nivel de uniformidad del color con respecto a la percepci��n visual. Esta tesis est�� organizada en siete cap��tulos. Despu��s de un cap��tulo inicial que presenta la motivaci��n que ha guiado la investigaci��n de esta tesis, en el cap��tulo 2 se presentan los fundamentos cient��ficos de la uniformidad del color en luces concentradas, como son: el espacio de color aplicado CIELAB, la percepci��n visual del color, los fundamentos de dise��o de focos respecto a los motores de luz y ��pticas no formadoras de im��genes, y los ��ltimos avances en la evaluaci��n de la uniformidad del color en el campo de los focos. El cap��tulo 3 desarrolla diferentes m��todos para la descripci��n matem��tica de la distribuci��n espacial del color en un ��rea definida, como son la diferencia de color m��xima, la desviaci��n media del color, el gradiente de la distribuci��n espacial de color, as�� como la suavidad radial y axial. Cada funci��n se refiere a los diferentes factores que influyen en la visi��n, los cuales necesitan un tratamiento distinto que el de los datos que se tendr��n en cuenta, adem��s de funciones de ponderaci��n que pre- y post-procesan los datos simulados o medidos para la reducci��n del ruido, la luminancia de corte, la aplicaci��n de la ponderaci��n de luminancia, la funci��n de sensibilidad de contraste, y la funci��n de distribuci��n acumulativa. En el cap��tulo 4, se obtiene la funci��n de m��rito Usl para la estimaci��n de la uniformidad del color percibida en focos. Se bas�� en los resultados de dos conjuntos de experimentos con factor humano realizados para evaluar la percepci��n visual de los sujetos de los patrones de focos t��picos. El primer experimento con factor humano dio lugar al orden de importancia percibida de los focos. El orden de rango percibido se utiliz�� para correlacionar las descripciones matem��ticas de las funciones b��sicas y la funci��n ponderada sobre la distribuci��n espacial del color, que condujo a la funci��n Usl. El segundo experimento con factor humano prob�� la percepci��n de los focos bajo condiciones ambientales diversas, con el objetivo de proporcionar una escala absoluta para Usl, para poder as�� sustituir la opini��n subjetiva personal de los individuos por una funci��n de m��rito estandarizada. La validaci��n de la funci��n Usl se presenta en relaci��n con el alcance de la aplicaci��n y condiciones, as�� como las limitaciones y restricciones que se realizan en el cap��tulo 5. Se compararon los datos medidos y simulados de varios sistemas ��pticos. Se discuten los campos de aplicaci��n , as�� como validaciones y restricciones de la funci��n. El cap��tulo 6 presenta el dise��o del sistema de focos y su optimizaci��n. Una evaluaci��n muestra el an��lisis de sistemas basados en el reflector y la lente TIR. Los sistemas ��pticos simulados se comparan en la uniformidad del color Usl, sensibilidad a las sombras coloreadas, eficiencia e intensidad luminosa m��xima. Se ha comprobado que no hay un sistema ��nico que obtenga los mejores resultados en todas las categor��as, y que una excelente uniformidad de color se pudo alcanzar por la conjunci��n de dos sistemas diferentes. Finalmente, el cap��tulo 7 presenta el resumen de esta tesis y la perspectiva para investigar otros aspectos. ABSTRACT Illumination with light-emitting diodes (LED) is more and more replacing traditional light sources. They provide advantages in efficiency, energy consumption, design, size and light quality. For more than 50 years, researchers have been working on LED improvements. Their main relevance for illumination is rapidly increasing. This thesis is focused on one important field of application which are spotlights. They are used to focus light on defined areas, outstanding objects in professional conditions. This high performance illumination required a defined light quality including tunable correlated color temperatures (CCT), high color rendering index (CRI), high efficiencies and bright, vivid colors. Several differently colored chips (red, blue, phosphor converted) in the LED package are combined to meet spectral power distribution with high CRI, tunable white and several light colors and secondary optics are used to collimate the light into the desired narrow spots with defined angle of emission. The combination of multi-color LED source and optical elements may cause chromatic inhomogeneities in spatial and angular light distribution which needs to solved at the optical design. However, there is no need for perfect uniformity in the spot light due to threshold in visual perception of human eye. Therefore, a mathematical description of color uniformity level with regard to visual perception is required. This thesis is organized seven seven chapters. After an initial one presenting the motivation that has guided the research of this thesis, Chapter 2 introduces the scientific basics of color uniformity in spot lights including: the applied color space CIELAB, the visual color perception, the spotlight design fundamentals with regards to light engines and nonimaging optics, and the state of the art for the evaluation of color uniformity in the far field of spotlights. Chapter 3 develops different methods for mathematical description of spatial color distribution in a defined area, which are the maximum color difference, the average color deviation, the gradient of spatial color distribution as well as the radial and axial smoothness. Each function refers to different visual influencing factors, and they need different handling of data be taken into account, along with weighting functions which pre- and post-process the simulated or measured data for noise reduction, luminance cutoff, the implementation of luminance weighting, contrast sensitivity function, and cumulative distribution function. In chapter 4, the merit function Usl for the estimation of the perceived color uniformity in spotlights is derived. It was based on the results of two sets of human factor experiments performed to evaluate the visual perception of typical spotlight patterns by subjects. The first human factor experiment resulted in the perceived rank order of the spotlights. The perceived rank order was used to correlate the mathematical descriptions of basic functions and weighted function concerning the spatial color distribution, which lead to the Usl function. The second human factor experiment tested the perception of spotlights under varied environmental conditions, with to objective to provide an absolute scale for Usl, so the subjective personal opinion of individuals could be replaced by a standardized merit function. The validation of the Usl function is presented concerning the application range and conditions as well as limitations and restrictions in carried out in chapter 5. Measured and simulated data of various optical several systems were compared. Fields of applications are discussed as well as validations and restrictions of the function. Chapter 6 presents spotlight system design and their optimization. An evaluation shows the analysis of reflector-based and TIR lens systems. The simulated optical systems are compared in color uniformity Usl , sensitivity to colored shadows, efficiency, and peak luminous intensity. It has been found that no single system which performed best in all categories, and that excellent color uniformity could be reached by two different system assemblies. Finally, chapter 7 summarizes the conclusions of the present thesis and an outlook for further investigation topics.

Post-�����occupancy monitoring of two flats in Madrid: development and assessment of a mixed methods methodology

Recent research has shown large differences between the expected and the actual energy consumption in buildings. The differences have been attributed partially, to the assumptions made during the design phase of buildings when simulation methods are employed. More accurate occupancy profiles on building operation could help to carry out more precise building performance calculations. This study focuses on the post-occupancy evaluation of two apartments, one renovated and one non renovated, in Madrid within the same building complex. The aim of this paper is to present an application of the mixed-methods methodology (Creswell, 2007) to assess thermal comfort and occupancy practices used in the case studies, and to discuss the shortcomings and opportunities associated with it. The mixed-methods methodology offers strategies for integrating qualitative and quantitative methods to investigate complex phenomena. This approach is expected to contribute to the growing knowledge of occupants��� behaviour and building performance by explaining the differences observed between energy consumption and thermal comfort in relation to people���s saving and comfort practices and the related experiences, preferences and values.

Image processing methods for human brain connectivity analysis from in-vivo diffusion MRI

The structural connectivity of the brain is considered to encode species-wise and subject-wise patterns that will unlock large areas of understanding of the human brain. Currently, diffusion MRI of the living brain enables to map the microstructure of tissue, allowing to track the pathways of fiber bundles connecting the cortical regions across the brain. These bundles are summarized in a network representation called connectome that is analyzed using graph theory. The extraction of the connectome from diffusion MRI requires a large processing flow including image enhancement, reconstruction, segmentation, registration, diffusion tracking, etc. Although a concerted effort has been devoted to the definition of standard pipelines for the connectome extraction, it is still crucial to define quality assessment protocols of these workflows. The definition of quality control protocols is hindered by the complexity of the pipelines under test and the absolute lack of gold-standards for diffusion MRI data. Here we characterize the impact on structural connectivity workflows of the geometrical deformation typically shown by diffusion MRI data due to the inhomogeneity of magnetic susceptibility across the imaged object. We propose an evaluation framework to compare the existing methodologies to correct for these artifacts including whole-brain realistic phantoms. Additionally, we design and implement an image segmentation and registration method to avoid performing the correction task and to enable processing in the native space of diffusion data. We release PySDCev, an evaluation framework for the quality control of connectivity pipelines, specialized in the study of susceptibility-derived distortions. In this context, we propose Diffantom, a whole-brain phantom that provides a solution to the lack of gold-standard data. The three correction methodologies under comparison performed reasonably, and it is difficult to determine which method is more advisable. We demonstrate that susceptibility-derived correction is necessary to increase the sensitivity of connectivity pipelines, at the cost of specificity. Finally, with the registration and segmentation tool called regseg we demonstrate how the problem of susceptibility-derived distortion can be overcome allowing data to be used in their original coordinates. This is crucial to increase the sensitivity of the whole pipeline without any loss in specificity.

A multidisciplinary reference framework to support innovative design, implementation and assessment of chronic care models

Hoy en d��a, por primera vez en la historia, la mayor parte de la poblaci��n podr�� vivir hasta los sesenta a��os y m��s (United Nations, 2015). Sin embargo, todav��a existe poca evidencia que demuestre que las personas mayores, est��n viviendo con mejor salud que sus padres, a la misma edad, ya que la mayor��a de los problemas de salud en edades avanzadas est��n asociados a las enfermedades cr��nicas (WHO, 2015). Los sistemas sanitarios de los pa��ses desarrollados funcionan adecuadamente cuando se trata del cuidado de enfermedades agudas, pero no son lo suficientemente eficaces en la gesti��n de las enfermedades cr��nicas. Durante la ��ltima d��cada, se han realizado esfuerzos para mejorar esta gesti��n, por medio de la utilizaci��n de estrategias de prevenci��n y de reenfoque de la provisi��n de los servicios de atenci��n para la salud (Kane et al. 2005). Seg��n una revisi��n sistem��tica de modelos de cuidado de salud, comisionada por el sistema nacional de salud Brit��nico, pocos modelos han conceptualizado cu��les son los componentes que hay que utilizar para proporcionar un cuidado cr��nico efectivo, y estos componentes no han sido suficientemente estructurados y articulados. Por lo tanto, no hay suficiente evidencia sobre el impacto real de cualquier modelo existente en la actualidad (Ham, 2006). Las innovaciones podr��an ayudar a conseguir mejores diagn��sticos, tratamientos y gesti��n de pacientes cr��nicos, as�� como a dar soporte a los profesionales y a los pacientes en el cuidado. Sin embargo, la forma en las que estas innovaciones se proporcionan no es lo suficientemente eficiente, efectiva y amigable para el usuario. Para mejorar esto, hace falta crear equipos de trabajo y estrategias multidisciplinares. En conclusi��n, hacen falta actividades que permitan conseguir que las innovaciones sean utilizadas en los sistemas de salud que quieren mejorar la gesti��n del cuidado cr��nico, para que sea posible: 1) traducir la ���atenci��n sanitaria basada en la evidencia��� en ���conocimiento factible���; 2) hacer frente a la complejidad de la atenci��n sanitaria a trav��s de una investigaci��n multidisciplinaria; 3) identificar una aproximaci��n sistem��tica para que se establezcan intervenciones innovadoras en el cuidado de salud. El marco de referencia desarrollado en este trabajo de investigaci��n es un intento de aportar estas mejoras. Las siguientes hip��tesis han sido propuestas: Hip��tesis 1: es posible definir un proceso de traducci��n que convierta un modelo de cuidado cr��nico en una descripci��n estructurada de objetivos, requisitos e indicadores clave de rendimiento. Hip��tesis 2: el proceso de traducci��n, si se ejecuta a trav��s de elementos basados en la evidencia, multidisciplinares y de orientaci��n econ��mica, puede convertir un modelo de cuidado cr��nico en un marco descriptivo, que define el ciclo de vida de soluciones innovadoras para el cuidado de enfermedades cr��nicas. Hip��tesis 3: es posible definir un m��todo para evaluar procesos, resultados y capacidad de desarrollar habilidades, y asistir equipos multidisciplinares en la creaci��n de soluciones innovadoras para el cuidado cr��nico. Hip��tesis 4: es posible dar soporte al desarrollo de soluciones innovadoras para el cuidado cr��nico a trav��s de un marco de referencia y conseguir efectos positivos, medidos en indicadores clave de rendimiento. Para verificar las hip��tesis, se ha definido una aproximaci��n metodol��gica compuesta de cuatro Fases, cada una asociada a una hip��tesis. Antes de esto, se ha llevado a cabo una ���Fase 0���, donde se han analizado los antecedentes sobre el problema (i.e. adopci��n sistem��tica de la innovaci��n en el cuidado cr��nico) desde una perspectiva multi-dominio y multi-disciplinar. Durante la fase 1, se ha desarrollado un Proceso de Traducci��n del Conocimiento, elaborado a partir del JBI Joanna Briggs Institute (JBI) model of evidence-based healthcare (Pearson, 2005), y sobre el cual se han definido cuatro Bloques de Innovaci��n. Estos bloques consisten en una descripci��n de elementos innovadores, definidos en la fase 0, que han sido a��adidos a los cuatros elementos que componen el modelo JBI. El trabajo llevado a cabo en esta fase ha servido tambi��n para definir los materiales que el proceso de traducci��n tiene que ejecutar. La traducci��n que se ha llevado a cabo en la fase 2, y que traduce la mejor evidencia disponible de cuidado cr��nico en acci��n: resultado de este proceso de traducci��n es la parte descriptiva del marco de referencia, que consiste en una descripci��n de un modelo de cuidado cr��nico (se ha elegido el Chronic Care Model, Wagner, 1996) en t��rminos de objetivos, especificaciones e indicadores clave de rendimiento y organizada en tres ciclos de innovaci��n (dise��o, implementaci��n y evaluaci��n). Este resultado ha permitido verificar la segunda hip��tesis. Durante la fase 3, para demostrar la tercera hip��tesis, se ha desarrollado un m��todo-mixto de evaluaci��n de equipos multidisciplinares que trabajan en innovaciones para el cuidado cr��nico. Este m��todo se ha creado a partir del m��todo mixto usado para la evaluaci��n de equipo multidisciplinares translacionales (Wooden, 2013). El m��todo creado a��ade una dimensi��n procedural al marco. El resultado de esta fase consiste, por lo tanto, en una primera versi��n del marco de referencia, lista para ser experimentada. En la fase 4, se ha validado el marco a trav��s de un caso de estudio multinivel y con t��cnicas de observaci��n-participante como m��todo de recolecci��n de datos. Como caso de estudio se han elegido las actividades de investigaci��n que el grupo de investigaci��n LifeStech ha desarrollado desde el 2008 para mejorar la gesti��n de la diabetes, actividades realizadas en un contexto internacional. Los resultados demuestran que el marco ha permitido mejorar las actividades de trabajo en distintos niveles: 1) la calidad y cantidad de las publicaciones; 2) se han conseguido dos contratos de investigaci��n sobre diabetes: el primero es un proyecto de investigaci��n aplicada, el segundo es un proyecto financiado para acelerar las innovaciones en el mercado; 3) a trav��s de los indicadores claves de rendimiento propuestos en el marco, una prueba de concepto de un prototipo desarrollado en un proyecto de investigaci��n ha sido transformada en una evaluaci��n temprana de una intervenci��n eHealth para el manejo de la diabetes, que ha sido recientemente incluida en Repositorio de pr��cticas innovadoras del Partenariado de Innovaci��n Europeo en Envejecimiento saludable y activo. La verificaci��n de las 4 hip��tesis ha permitido demonstrar la hip��tesis principal de este trabajo de investigaci��n: es posible contribuir a crear un puente entre la atenci��n sanitaria y la innovaci��n y, por lo tanto, mejorar la manera en que el cuidado cr��nico sea procurado en los sistemas sanitarios. ABSTRACT Nowadays, for the first time in history, most people can expect to live into their sixties and beyond (United Nations, 2015). However, little evidence suggests that older people are experiencing better health than their parents, and most of the health problems of older age are linked to Chronic Diseases (WHO, 2015). The established health care systems in developed countries are well suited to the treatment of acute diseases but are mostly inadequate for dealing with CDs. Healthcare systems are challenging the burden of chronic diseases by putting more emphasis on the prevention of disease and by looking for new ways to reorient the provision of care (Kane et al., 2005). According to an evidence-based review commissioned by the British NHS Institute, few models have conceptualized effective components of care for CDs and these components have been not structured and articulated. ���Consequently, there is limited evidence about the real impact of any of the existing models��� (Ham, 2006). Innovations could support to achieve better diagnosis, treatment and management for patients across the continuum of care, by supporting health professionals and empowering patients to take responsibility. However, the way they are delivered is not sufficiently efficient, effective and consumer friendly. The improvement of innovation delivery, involves the creation of multidisciplinary research teams and taskforces, rather than just working teams. There are several actions to improve the adoption of innovations from healthcare systems that are tackling the epidemics of CDs: 1) Translate Evidence-Based Healthcare (EBH) into actionable knowledge; 2) Face the complexity of healthcare through multidisciplinary research; 3) Identify a systematic approach to support effective implementation of healthcare interventions through innovation. The framework proposed in this research work is an attempt to provide these improvements. The following hypotheses have been drafted: ������Hypothesis 1: it is possible to define a translation process to convert a model of chronic care into a structured description of goals, requirements and key performance indicators. ������Hypothesis 2: a translation process, if executed through evidence-based, multidisciplinary, holistic and business-oriented elements, can convert a model of chronic care in a descriptive framework, which defines the whole development cycle of innovative solutions for chronic disease management. ������Hypothesis 3: it is possible to design a method to evaluate processes, outcomes and skill acquisition capacities, and assist multidisciplinary research teams in the creation of innovative solutions for chronic disease management. ������Hypothesis 4: it is possible to assist the development of innovative solutions for chronic disease management through a reference framework and produce positive effects, measured through key performance indicators. In order to verify the hypotheses, a methodological approach, composed of four Phases that correspond to each one of the stated hypothesis, was defined. Prior to this, a ���Phase 0���, consisting in a multi-domain and multi-disciplinary background analysis of the problem (i.e.: systematic adoption of innovation to chronic care), was carried out. During phase 1, in order to verify the first hypothesis, a Knowledge Translation Process (KTP) was developed, starting from the JBI Joanna Briggs Institute (JBI) model of evidence-based healthcare was used (Pearson, 2005) and adding Four Innovation Blocks. These blocks represent an enriched description, added to the JBI model, to accelerate the transformation of evidence-healthcare through innovation; the innovation blocks are built on top of the conclusions drawn after Phase 0. The background analysis gave also indication on the materials and methods to be used for the execution of the KTP, carried out during phase 2, that translates the actual best available evidence for chronic care into action: this resulted in a descriptive Framework, which is a description of a model of chronic care (the Chronic Care Model was chosen, Wagner, 1996) in terms of goals, specified requirements and Key Performance Indicators, and articulated in the three development cycles of innovation (i.e. design, implementation and evaluation). Thanks to this result the second hypothesis was verified. During phase 3, in order to verify the third hypothesis, a mixed-method to evaluate multidisciplinary teams working on innovations for chronic care, was created, based on a mixed-method used for the evaluation of Multidisciplinary Translational Teams (Wooden, 2013). This method adds a procedural dimension to the descriptive component of the Framework, The result of this phase consisted in a draft version of the framework, ready to be tested in a real scenario. During phase 4, a single and multilevel case study, with participant-observation data collection, was carried out, in order to have a complete but at the same time multi-sectorial evaluation of the framework. The activities that the LifeStech research group carried out since 2008 to improve the management of diabetes have been selected as case study. The results achieved showed that the framework allowed to improve the research activities in different directions: the quality and quantity of the research publications that LifeStech has issued, have increased substantially; 2 project grants to improve the management of diabetes, have been assigned: the first is a grant funding applied research while the second is about accelerating innovations into the market; by using the assessment KPIs of the framework, the proof of concept validation of a prototype developed in a research project was transformed into an early stage assessment of innovative eHealth intervention for Diabetes Management, which has been recently included in the repository of innovative practice of the European Innovation Partnership on Active and Health Ageing initiative. The verification of the 4 hypotheses lead to verify the main hypothesis of this research work: it is possible to contribute to bridge the gap between healthcare and innovation and, in turn, improve the way chronic care is delivered by healthcare systems.

Contribution to the analysis and design of reflectarray antennas for reconfigurable beam applications at frequencies above 100 GHz using liquid crystal technology

El trabajo contenido en esta tesis doctoral est�� encuadrado en el desarrollo de antenas reconfigurables electr��nicamente capaces de proporcionar prestaciones competitivas a las aplicaciones cada vez m��s comunes que operan a frecuencias superiores a 60 GHz. En concreto, esta tesis se centra en el estudio, dise��o, e implementaci��n de las antenas reflectarray, a las que se introduce la tecnolog��a de cristal l��quido como elemento caracter��stico con el que se consigue reconfigurabilidad de haz de forma electr��nica. Desde un punto de vista muy general, se puede describir un cristal l��quido como un material cuya permitividad el��ctrica es variable y controlada por una excitaci��n externa, que generalmente suele corresponderse con un campo el��ctrico quasi-est��tico (AC). Las antenas reflectarray de cristal l��quido se han escogido como objeto de estudio por varias razones. La primera de ellas tiene que ver con las ventajas que los reflectarrays, y en especial aquellos realizados en configuraci��n planar, proporcionan con respecto a otras antenas de alta ganancia como los reflectores o los ���phased-arrays���. En los reflectarrays, la alimentaci��n a trav��s de una fuente primaria com��n (caracter��stica de reflectores) y el elevado n��mero de grados de libertad de las celdas que los componen (caracter��stica de arrays) hacen que estas antenas puedan proporcionar prestaciones el��ctricas iguales o mejores que las anteriores, a un coste m��s reducido y con estructuras de antena m��s compactas. La segunda raz��n radica en la flexibilidad que ofrece el cristal l��quido a ser confinado y polarizado en recintos de geometr��a variada, como consecuencia de su fluidez (propiedad de los l��quidos). Por ello, la tecnolog��a de cristal l��quido permite que el propio elemento reconfigurable en las celdas de reflectarray se adapte a la configuraci��n planar de manera que en s�� mismo, el cristal l��quido sea una o varias de las capas caracter��sticas de esta configuraci��n. Esto simplifica de forma dr��stica la estructura y la fabricaci��n de este tipo de antenas, incluso si se comparan con reflectarrays reconfigurables basados en otras tecnolog��as como diodos, MEMS, etc. Por tanto, su coste y desarrollo es muy reducido, lo que hace que se puedan fabricar reflectarrays reconfigurables el��ctricamente grandes, a bajo coste, y en producci��n elevada. Un ejemplo claro de una estructura similar, y que ha tenido ��xito comercial, son las pantallas de cristal l��quido. La tercera raz��n reside en el hecho de que el cristal l��quido es, hasta la fecha, de las pocas tecnolog��as capaces de ofrecer reconfigurabilidad del haz a frecuencias superiores a 60 GHz. De hecho, el cristal l��quido permite reconfigurabilidad en un amplio margen de frecuencias, que va desde DC a frecuencias del espectro visible, incluyendo las microondas y los THz. Otras tecnolog��as, como los materiales ferroel��ctricos, el grafeno o la tecnolog��a CMOS ���on chip��� permiten tambi��n conmutar el haz en estas frecuencias. Sin embargo, la tecnolog��a CMOS tiene un elevado coste y actualmente est�� limitada a frecuencias inferiores a 150 GHz, y aunque los materiales ferroel��ctricos o el grafeno puedan conmutar a frecuencias m��s altas y en un rango m��s amplio, tienen serias dificultades que los hacen a��n inmaduros. En el caso de los materiales ferroel��ctricos, los elevados voltajes para conmutar el material los hacen poco atractivos, mientras que en el caso del grafeno, su modelado a��n est�� en discusi��n, y todav��a no se han arrojado resultados experimentales que validen su idoneidad. Estas tres razones hacen que los reflectarrays basados en cristal l��quido sean atractivos para multitud de aplicaciones de haz reconfigurable a frecuencias superiores a 60 GHz. Aplicaciones como radar de escaneo de im��genes de alta resoluci��n, espectroscopia molecular, radi��metros para observaci��n atmosf��rica, o comunicaciones inal��mbricas de alta frecuencia (WiGig) son algunas de ellas. La tesis est�� estructurada en tres partes. En la primera de ellas se describen las caracter��sticas m��s comunes de los cristales l��quidos, centr��ndonos en detalle en aquellas propiedades ofrecidas por este material en fase nem��tica. En concreto, se estudiar�� la anisotrop��a diel��ctrica (Ae) de los cristales l��quidos uniaxiales, que son los que se emplean en esta tesis, definida como la diferencia entre la permitividad paralela (��//) y la perpendicular (e��): Ae = e,, - e��. Tambi��n se estudiar�� la variaci��n de este par��metro (Ae) con la frecuencia, y el modelado electromagn��tico macrosc��pico m��s general que, extra��do a partir de aquella, permite describir el cristal l��quido para cada tensi��n de polarizaci��n en celdas de geometr��a planar. Este modelo es de suma importancia para garantizar precisi��n en el desfasaje proporcionado por las diferentes celdas reconfigurables para reflectarrays que se describir��n en la siguiente parte de la tesis. La segunda parte de la tesis se centra en el dise��o de celdas reflectarray resonantes basadas en cristal l��quido. La raz��n por la que se escogen estos tipos de celdas reside en el hecho de que son las ��nicas capaces de proporcionar rangos de fase elevados ante la reducida anisotrop��a diel��ctrica que ofrecen los cristales l��quidos. El objetivo de esta parte trata, por tanto, de obtener estructuras de celdas reflectarray que sean capaces de proporcionar buenas prestaciones el��ctricas a nivel de antena, mejorando sustancialmente las prestaciones de las celdas reportadas en el estado del arte, as�� como de desarrollar una herramienta de dise��o general para aquellas. Para ello, se estudian las prestaciones el��ctricas de diferentes tipos de elementos resonantes de cristal l��quido que van, desde el m��s sencillo, que ha limitado el estado de la t��cnica hasta el desarrollo de esta tesis y que est�� formado por un s��lo resonador, a elementos que constan de varios resonadores (multi-resonantes) y que pueden ser monocapa o multicapa. En un primer paso, el procedimiento de dise��o de estas estructuras hace uso de un modelo convencional de cristal l��quido que ha venido siendo usado en el estado del arte para este tipo de celdas, y que considera el cristal l��quido como un material homog��neo e is��tropo cuya permitividad var��a entre (e/7) y (e��). Sin embargo, en esta parte de la tesis se demuestra que dicho modelado no es suficiente para describir de forma gen��rica el comportamiento del cristal l��quido en las celdas tipo reflectarray. En la tesis se proponen procedimientos m��s exactos para el an��lisis y dise��o basados en un modelo m��s general que define el cristal l��quido como un material anis��tropo e inhomogeneo en tres dimensiones, y se ha implementado una t��cnica que permite optimizar celdas multi-resonantes de forma eficiente para conseguir elevadas prestaciones en cuanto a ancho de banda, rango de fase, p��rdidas, o sensibilidad al ��ngulo de incidencia. Los errores cometidos en el uso del modelado convencional a nivel de celda (amplitud y fase) se han analizado para varias geometr��as, usando medidas de varios prototipos de antena que usan un cristal l��quido real a frecuencias superiores a 100 GHz. Las medidas se han realizado en entorno peri��dico mediante un banco cuasi-��ptico, que ha sido dise��ado especialmente para este fin. Uno de estos prototipos se ha optimizado a 100 GHz para conseguir un ancho de banda relativamente elevado (10%), p��rdidas reducidas, un rango de fase mayor de 360��, baja sensibilidad al ��ngulo de incidencia, y baja influencia de la inhomogeneidad transversal del cristal l��quido en la celda. Estas prestaciones a nivel de celda superan de forma clara aquellas conseguidas por otros elementos que se han reportado en la literatura, de manera que dicho prototipo se ha usado en la ��ltima parte de la tesis para realizar diversas antenas de barrido. Finalmente, en esta parte se presenta una estrategia de caracterizaci��n de la anisotrop��a macrosc��pica a partir de medidas de los elementos de reflectarray dise��ados en banco cuasi-��ptico, obteniendo resultados tanto en las frecuencias de inter��s en RF como en AC, y compar��ndolas con aquellas obtenidas mediante otros m��todos. La tercera parte de la tesis consiste en el estudio, dise��o, fabricaci��n y medida de antenas reconfigurables basadas en cristal l��quido en configuraciones complejas. En reflectarrays pasivos, el procedimiento de dise��o de la antena se limita ��nicamente al ajuste en cada celda de la antena de las dimensiones de las metalizaciones que se emplean para el control de fase, mediante procesos de optimizaci��n bien conocidos. Sin embargo, en el caso de reflectarrays reconfigurables basados en cristal l��quido, resulta necesario un paso adicional, que consiste en calcular de forma adecuada las tensiones de control en cada celda del reflectarray para configurar la fase requerida en cada una de ellas, as�� como dise��ar la estructura y los circuitos de control que permitan direccionar a cada elemento su tensi��n correspondiente. La s��ntesis de tensiones es por tanto igual o m��s importante que el dise��o de la geometr��a de las celdas, puesto que ��stas son las que est��n directamente relacionadas con la fase. En el estado del arte, existen varias estrategias de s��ntesis de tensiones que se basan en la caracterizaci��n experimental de la curva de fase respecto al voltaje. Sin embargo, esta caracterizaci��n s��lo puede hacerse a un solo ��ngulo de incidencia y para unas determinadas dimensiones de celda, lo que produce que las tensiones sintetizadas sean diferentes de las adecuadas, y en definitiva que se alcancen errores de fase mayores de 70��. De esta forma, hasta la fecha, las prestaciones a nivel de antena que se han conseguido son reducidas en cuanto a ancho de banda, rango de escaneo o nivel de l��bulos secundarios. En esta ��ltima parte de la tesis, se introduce una nueva estrategia de s��ntesis de tensiones que es capaz de predecir mediante simulaciones, y con alta precisi��n, las tensiones que deben introducirse en cada celda teniendo en cuenta su ��ngulo de incidencia, sus dimensiones, la frecuencia, as�� como la se��al de polarizaci��n definida por su frecuencia y forma de onda AC. Esta estrategia se basa en modelar cada uno de los estados de permitividad del cristal l��quido como un sustrato anis��tropo con inhomogeneidad longitudinal (1D), o en ciertos casos, como un tensor equivalente homog��neo. La precisi��n de ambos modelos electromagn��ticos tambi��n se discute. Con el objetivo de obtener una herramienta eficiente de c��lculo de tensiones, tambi��n se ha escrito e implementado una herramienta de an��lisis basada en el M��todo de los Momentos en el Dominio Espectral (SD-MoM) para sustratos estratificados anis��tropos, que se usa en cada iteraci��n del procedimiento de s��ntesis para analizar cada una de las celdas de la antena. La s��ntesis de tensiones se ha dise��ado adem��s para reducir al m��ximo el efecto del rizado de amplitud en el diagrama de radiaci��n, que es caracter��stico en los reflectarrays que est��n formados por celdas con p��rdidas elevadas, lo que en s��, supone un avance adicional para la obtenci��n de mejores prestaciones de antena. Para el c��lculo de los diagramas de radiaci��n empleados en el procedimiento de s��ntesis, se asume un an��lisis elemento a elemento considerando periodicidad local, y se propone el uso de un m��todo capaz de modelar el campo incidente de forma que se elimine la limitaci��n de la periodicidad local en la excitaci��n. Una vez definida la estrategia adecuada de c��lculo de las tensiones a aplicar al cristal l��quido en cada celda, la estructura de direccionamiento de las mismas en la antena, y dise��ados los circuitos de control, se dise��an, fabrican y miden dos prototipos diferentes de antena de barrido electr��nico a 100 GHz usando las celdas anteriormente presentadas. El primero de estos prototipos es un reflectarray en configuraci��n ���single offset��� con capacidad de escaneo en un plano (elevaci��n o azimut). Aunque previamente se realizan dise��os de antenas de barrido en 2D a varias frecuencias en el rango de milim��tricas y sub-milim��tricas, y se proponen ciertas estrategias de direccionamiento que permiten conseguir este objetivo, se desarrolla el prototipo con direccionamiento en una dimensi��n con el fin de reducir el n��mero de controles y posibles errores de fabricaci��n, y as�� tambi��n validar la herramienta de dise��o. Para un tama��o medio de apertura (con un numero de filas y columnas entre 30 y 50 elementos, lo que significa un reflectarray con un n��mero de elementos superior a 900), la configuraci��n ���single offset��� proporciona rangos de escaneo elevados, y ganancias que pueden oscilar entre los 20 y 30 dBi. En concreto, el prototipo medido proporciona un haz de barrido en un rango angular de 55��, en el que el nivel de l��bulos secundarios (SLL) permanece mejor de -13 dB en un ancho de banda de un 8%. La ganancia m��xima es de 19.4 dBi. Estas prestaciones superan de forma clara aquellas conseguidas por otros autores. El segundo prototipo se corresponde con una antena de doble reflector que usa el reflectarray de cristal l��quido como sub-reflector para escanear el haz en un plano (elevaci��n o azimut). El objetivo b��sico de esta geometr��a es obtener mayores ganancias que en el reflectarray ���single offset��� con una estructura m��s compacta, aunque a expensas de reducir el rango de barrido. En concreto, se obtiene una ganancia m��xima de 35 dBi, y un rango de barrido de 12��. Los procedimientos de s��ntesis de tensiones y de dise��o de las estructuras de las celdas forman, en su conjunto, una herramienta completa de dise��o precisa y eficiente de antenas reflectarray reconfigurables basados en cristales l��quidos. Dicha herramienta se ha validado mediante el dise��o, la fabricaci��n y la medida de los prototipos anteriormente citados a 100 GHz, que consiguen algo nunca alcanzado anteriormente en la investigaci��n de este tipo de antenas: unas prestaciones competitivas y una predicci��n excelente de los resultados. El procedimiento es general, y por tanto se puede usar a cualquier frecuencia en la que el cristal l��quido ofrezca anisotrop��a diel��ctrica, incluidos los THz. Los prototipos desarrollados en esta tesis doctoral suponen tambi��n unas de las primeras antenas de barrido real a frecuencias superiores a 100 GHz. En concreto, la antena de doble reflector para escaneo de haz es la primera antena reconfigurable electr��nicamente a frecuencias superiores a 60 GHz que superan los 25 dBi de ganancia, siendo a su vez la primera antena de doble reflector que contiene un reflectarray reconfigurable como sub-reflector. Finalmente, se proponen ciertas mejoras que a��n deben se deben realizar para hacer que estas antenas puedan ser un producto completamente desarrollado y competitivo en el mercado. ABSTRACT The work presented in this thesis is focused on the development of electronically reconfigurable antennas that are able to provide competitive electrical performance to the increasingly common applications operating at frequencies above 60 GHz. Specifically, this thesis presents the study, design, and implementation of reflectarray antennas, which incorporate liquid crystal (LC) materials to scan or reconfigure the beam electronically. From a general point of view, a liquid crystal can be defined as a material whose dielectric permittivity is variable and can be controlled with an external excitation, which usually corresponds with a quasi-static electric field (AC). By changing the dielectric permittivity at each cell that makes up the reflectarray, the phase shift on the aperture is controlled, so that a prescribed radiation pattern can be configured. Liquid Crystal-based reflectarrays have been chosen for several reasons. The first has to do with the advantages provided by the reflectarray antenna with respect to other high gain antennas, such as reflectors or phased arrays. The RF feeding in reflectarrays is achieved by using a common primary source (as in reflectors). This arrangement and the large number of degrees of freedom provided by the cells that make up the reflectarray (as in arrays), allow these antennas to provide a similar or even better electrical performance than other low profile antennas (reflectors and arrays), but assuming a more reduced cost and compactness. The second reason is the flexibility of the liquid crystal to be confined in an arbitrary geometry due to its fluidity (property of liquids). Therefore, the liquid crystal is able to adapt to a planar geometry so that it is one or more of the typical layers of this configuration. This simplifies drastically both the structure and manufacture of this type of antenna, even when compared with reconfigurable reflectarrays based on other technologies, such as diodes MEMS, etc. Therefore, the cost of developing this type of antenna is very small, which means that electrically large reconfigurable reflectarrays could be manufactured assuming low cost and greater productions. A paradigmatic example of a similar structure is the liquid crystal panel, which has already been commercialized successfully. The third reason lies in the fact that, at present, the liquid crystal is one of the few technologies capable of providing switching capabilities at frequencies above 60 GHz. In fact, the liquid crystal allows its permittivity to be switched in a wide range of frequencies, which are from DC to the visible spectrum, including microwaves and THz. Other technologies, such as ferroelectric materials, graphene or CMOS "on chip" technology also allow the beam to be switched at these frequencies. However, CMOS technology is expensive and is currently limited to frequencies below 150 GHz, and although ferroelectric materials or graphene can switch at higher frequencies and in a wider range, they have serious difficulties that make them immature. Ferroelectric materials involve the use of very high voltages to switch the material, making them unattractive, whereas the electromagnetic modelling of the graphene is still under discussion, so that the experimental results of devices based on this latter technology have not been reported yet. These three reasons make LC-based reflectarrays attractive for many applications that involve the use of electronically reconfigurable beams at frequencies beyond 60 GHz. Applications such as high resolution imaging radars, molecular spectroscopy, radiometers for atmospheric observation, or high frequency wireless communications (WiGig) are just some of them. This thesis is divided into three parts. In the first part, the most common properties of the liquid crystal materials are described, especially those exhibited in the nematic phase. The study is focused on the dielectric anisotropy (Ac) of uniaxial liquid crystals, which is defined as the difference between the parallel (e/7) and perpendicular (e��) permittivities: Ae = e,, - e��. This parameter allows the permittivity of a LC confined in an arbitrary volume at a certain biasing voltage to be described by solving a variational problem that involves both the electrostatic and elastic energies. Thus, the frequency dependence of (Ae) is also described and characterised. Note that an appropriate LC modelling is quite important to ensure enough accuracy in the phase shift provided by each cell that makes up the reflectarray, and therefore to achieve a good electrical performance at the antenna level. The second part of the thesis is focused on the design of resonant reflectarray cells based on liquid crystal. The reason why resonant cells have been chosen lies in the fact that they are able to provide enough phase range using the values of the dielectric anisotropy of the liquid crystals, which are typically small. Thus, the aim of this part is to investigate several reflectarray cell architectures capable of providing good electrical performance at the antenna level, which significantly improve the electrical performance of the cells reported in the literature. Similarly, another of the objectives is to develop a general tool to design these cells. To fulfill these objectives, the electrical yields of different types of resonant reflectarray elements are investigated, beginning from the simplest, which is made up of a single resonator and limits the state of the art. To overcome the electrical limitations of the single resonant cell, several elements consisting of multiple resonators are considered, which can be single-layer or multilayer. In a first step, the design procedure of these structures makes use of a conventional electromagnetic model which has been used in the literature, which considers that the liquid crystal behaves as homogeneous and isotropic materials whose permittivity varies between (e/7) y (e��). However, in this part of the thesis it is shown that the conventional modelling is not enough to describe the physical behaviour of the liquid crystal in reflectarray cells accurately. Therefore, a more accurate analysis and design procedure based on a more general model is proposed and developed, which defines the liquid crystal as an anisotropic three-dimensional inhomogeneous material. The design procedure is able to optimize multi-resonant cells efficiently to achieve good electrical performance in terms of bandwidth, phase range, losses, or sensitivity to the angle of incidence. The errors made when the conventional modelling (amplitude and phase) is considered have been also analysed for various cell geometries, by using measured results from several antenna prototypes made up of real liquid crystals at frequencies above 100 GHz. The measurements have been performed in a periodic environment using a quasi-optical bench, which has been designed especially for this purpose. One of these prototypes has been optimized to achieve a relatively large bandwidth (10%) at 100 GHz, low losses, a phase range of more than 360��, a low sensitivity to angle of incidence, and a low influence of the transversal inhomogeneity of the liquid crystal in the cell. The electrical yields of this prototype at the cell level improve those achieved by other elements reported in the literature, so that this prototype has been used in the last part of the thesis to perform several complete antennas for beam scanning applications. Finally, in this second part of the thesis, a novel strategy to characterise the macroscopic anisotropy using reflectarray cells is presented. The results in both RF and AC frequencies are compared with those obtained by other methods. The third part of the thesis consists on the study, design, manufacture and testing of LCbased reflectarray antennas in complex configurations. Note that the design procedure of a passive reflectarray antenna just consists on finding out the dimensions of the metallisations of each cell (which are used for phase control), using well-known optimization processes. However, in the case of reconfigurable reflectarrays based on liquid crystals, an additional step must be taken into account, which consists of accurately calculating the control voltages to be applied to each cell to configure the required phase-shift distribution on the surface of the antenna. Similarly, the structure to address the voltages at each cell and the control circuitry must be also considered. Therefore, the voltage synthesis is even more important than the design of the cell geometries (dimensions), since the voltages are directly related to the phase-shift. Several voltage synthesis procedures have been proposed in the state of the art, which are based on the experimental characterization of the phase/voltage curve. However, this characterization can be only carried out at a single angle of incidence and at certain cell dimensions, so that the synthesized voltages are different from those needed, thus giving rise to phase errors of more than 70��. Thus, the electrical yields of the LCreflectarrays reported in the literature are limited in terms of bandwidth, scanning range or side lobes level. In this last part of the thesis, a new voltage synthesis procedure has been defined and developed, which allows the required voltage to be calculated at each cell using simulations that take into account the particular dimensions of the cells, their angles of incidence, the frequency, and the AC biasing signal (frequency and waveform). The strategy is based on the modelling of each one of the permittivity states of the liquid crystal as an anisotropic substrate with longitudinal inhomogeneity (1D), or in certain cases, as an equivalent homogeneous tensor. The accuracy of both electromagnetic models is also discussed. The phase errors made by using the proposed voltage synthesis are better than 7��. In order to obtain an efficient tool to analyse and design the reflectarray, an electromagnetic analysis tool based on the Method of Moments in the spectral domain (SD-MoM) has also written and developed for anisotropic stratified media, which is used at each iteration of the voltage synthesis procedure. The voltage synthesis is also designed to minimize the effect of amplitude ripple on the radiation pattern, which is typical of reflectarrays made up of cells exhibiting high losses and represents a further advance in achieving a better antenna performance. To calculate the radiation patterns used in the synthesis procedure, an element-by-element analysis is assumed, which considers the local periodicity approach. Under this consideration, the use of a novel method is proposed, which avoids the limitation that the local periodicity imposes on the excitation. Once the appropriate strategy to calculate the voltages to be applied at each cell is developed, and once it is designed and manufactured both the structure to address the voltages to the antenna and the control circuits, two complete LC-based reflectarray antennas that operate at 100 GHz have been designed, manufactured and tested using the previously presented cells. The first prototype consists of a single offset reflectarray with beam scanning capabilities on one plane (elevation and azimuth). Although several LC-reflectarray antennas that provide 2-D scanning capabilities are also designed, and certain strategies to achieve the 2-D addressing of the voltage are proposed, the manufactured prototype addresses the voltages in one dimension in order to reduce the number of controls and manufacturing errors, and thereby validating the design tool. For an average aperture size (with a number of rows and columns of between 30 and 50 elements, which means a reflectarray with more than 900 cells), the single offset configuration provides an antenna gain of between 20 and 30 dBi and a large scanning range. The prototype tested at 100 GHz exhibits an electronically scanned beam in an angular range of 55�� and 8% of bandwidth, in which the side lobe level (SLL) remains better than -13 dB. The maximum gain is 19.4 dBi. The electrical performance of the antenna is clearly an improvement on those achieved by other authors in the state of the art. The second prototype corresponds to a dual reflector antenna with a liquid crystal-based reflectarray used as a sub-reflector for beam scanning in one plane (azimuth or elevation). The main objective is to obtain a higher gain than that provided by the single offset configuration, but using a more compact architecture. In this case, a maximum gain of 35 dBi is achieved, although at the expense of reducing the scanning range to 12��, which is inherent in this type of structure. As a general statement, the voltage synthesis and the design procedure of the cells, jointly make up a complete, accurate and efficient design tool of reconfigurable reflectarray antennas based on liquid crystals. The tool has been validated by testing the previously mentioned prototypes at 100 GHz, which achieve something never reached before for this type of antenna: a competitive electrical performance, and an excellent prediction of the results. The design procedure is general and therefore can be used at any frequency for which the liquid crystal exhibits dielectric anisotropy. The two prototypes designed, manufactured and tested in this thesis are also some of the first antennas that currently operate at frequencies above 100 GHz. In fact, the dual reflector antenna is the first electronically scanned dual reflector antenna at frequencies above 60 GHz (the operation frequency is 100 GHz) with a gain greater than 25 dBi, being in turn the first dual-reflector antenna with a real reconfigurable sub-reflectarray. Finally, some improvements that should be still investigated to make these antennas commercially competitive are proposed.

M��todos diferenciales e interferom��tricos para la evaluaci��n de deformaciones de la corteza terrestre mediante t��cnicas GNSS e InSAR = Differential and interferometric methods for evaluation of crustal deformation using GNSS and InSAR techniques

La actividad volc��nica interviene en multitud de facetas de la propia actividad humana, no siempre negativas. Sin embargo, son m��s los motivos de peligrosidad y riesgo que incitan al estudio de la actividad volc��nica. Existen razones de seguridad que inciden en el mantenimiento del seguimiento y monitorizaci��n de la actividad volc��nica para garantizar la vida y la seguridad de los asentamientos antr��picos en las proximidades de los edificios volc��nicos. En esta tesis se define e implementa un sistema de monitorizaci��n de movimientos de la corteza en las islas de Tenerife y La Palma, donde el impacto social que representa un aumento o variaci��n de la actividad volc��nica en las islas es muy severo. Aparte de la alta densidad demogr��fica del Archipi��lago, esta poblaci��n aumenta significativamente, en diferentes periodos a lo largo del a��o, debido a la actividad tur��stica que representa la mayor fuente de ingresos de las islas. La poblaci��n y los centros tur��sticos se diseminan predominantemente a lo largo de las costas y tambi��n a lo largo de los flancos de los edificios volc��nicos. Quiz�� el mantenimiento de estas estructuras sociales y socio-econ��micas son los motivos m��s importantes que justifican una monitorizaci��n de la actividad volc��nica en las Islas Canarias. Recientemente se ha venido trabajando cada vez m��s en el intento de predecir la actividad volc��nica utilizando los nuevos sistemas de monitorizaci��n geod��sica, puesto que la actividad volc��nica se manifiesta anteriormente por deformaci��n de la corteza terrestre y cambios en la fuerza de la gravedad en la zona donde m��s tarde se registran eventos volc��nicos. Los nuevos dispositivos y sensores que se han desarrollado en los ��ltimos a��os en materias como la geodesia, la observaci��n de la Tierra desde el espacio y el posicionamiento por sat��lite, han permitido observar y medir tanto la deformaci��n producida en el terreno como los cambios de la fuerza de la gravedad antes, durante y posteriormente a los eventos volc��nicos que se producen. Estos nuevos dispositivos y sensores han cambiado las t��cnicas o metodolog��as geod��sicas que se ven��an utilizando hasta la aparici��n de los mismos, renovando m��todos cl��sicos y desarrollando otros nuevos que ya se est��n afianzando como metodolog��as probadas y reconocidas para ser usadas en la monitorizaci��n volc��nica. Desde finales de la d��cada de los noventa del siglo pasado se han venido desarrollando en las Islas Canarias varios proyectos que han tenido como objetivos principales el desarrollo de nuevas t��cnicas de observaci��n y monitorizaci��n por un lado y el dise��o de una metodolog��a de monitorizaci��n volc��nica adecuada, por otro. Se presenta aqu�� el estudio y desarrollo de t��cnicas GNSS para la monitorizaci��n de deformaciones corticales y su campo de velocidades para las islas de Tenerife y La Palma. En su implementaci��n, se ha tenido en cuenta el uso de la infraestructura geod��sica y de monitorizaci��n existente en el archipi��lago a fin de optimizar costes, adem��s de complementarla con nuevas estaciones para dar una cobertura total a las dos islas. Los resultados obtenidos en los proyectos, que se describen en esta memoria, han dado nuevas perspectivas en la monitorizaci��n geod��sica de la actividad volc��nica y nuevas zonas de inter��s que anteriormente no se conoc��an en el entorno de las Islas Canarias. Se ha tenido especial cuidado en el tratamiento y propagaci��n de los errores durante todo el proceso de observaci��n, medida y proceso de los datos registrados, todo ello en aras de cuantificar el grado de fiabilidad de los resultados obtenidos. Tambi��n en este sentido, los resultados obtenidos han sido verificados con otros procedentes de sistemas de observaci��n radar de sat��lite, incorporando adem��s a este estudio las implicaciones que el uso conjunto de tecnolog��as radar y GNSS tendr��n en un futuro en la monitorizaci��n de deformaciones de la corteza terrestre. ABSTRACT Volcanic activity occurs in many aspects of human activity, and not always in a negative manner. Nonetheless, research into volcanic activity is more likely to be motivated by its danger and risk. There are security reasons that influence the monitoring of volcanic activity in order to guarantee the life and safety of human settlements near volcanic edifices. This thesis defines and implements a monitoring system of movements in the Earth���s crust in the islands of Tenerife and La Palma, where the social impact of an increase (or variation) of volcanic activity is very severe. Aside from the high demographic density of the archipelago, the population increases significantly in different periods throughout the year due to tourism, which represents a major source of revenue for the islands. The population and the tourist centres are mainly spread along the coasts and also along the flanks of the volcanic edifices. Perhaps the preservation of these social and socio-economic structures is the most important reason that justifies monitoring volcanic activity in the Canary Islands. Recently more and more work has been done with the intention of predicting volcanic activity, using new geodesic monitoring systems, since volcanic activity is evident prior to eruption because of a deformation of the Earth���s crust and changes in the force of gravity in the zone where volcanic events will later be recorded. The new devices and sensors that have been developed in recent years in areas such as geodesy, the observation of the Earth from space, and satellite positioning have allowed us to observe and measure the deformation produced in the Earth as well as the changes in the force of gravity before, during, and after the volcanic events occur. The new devices and sensors have changed the geodetic techniques and methodologies that were used previously. The classic methods have been renovated and other newer ones developed that are now vouched for as proven recognised methodologies to be used for volcanic monitoring. Since the end of the 1990s, in the Canary Islands various projects have been developed whose principal aim has been the development of new observation and monitoring techniques on the one hand, and the design of an appropriate volcanic monitoring methodology on the other. The study and development of GNSS techniques for the monitoring of crustal deformations and their velocity field is presented here. To carry out the study, the use of geodetic infrastructure and existing monitoring in the archipelago have been taken into account in order to optimise costs, besides complementing it with new stations for total coverage on both islands. The results obtained in the projects, which are described below, have produced new perspectives in the geodetic monitoring of volcanic activity and new zones of interest which previously were unknown in the environment of the Canary Islands. Special care has been taken with the treatment and propagation of errors during the entire process of observing, measuring, and processing the recorded data. All of this was done in order to quantify the degree of trustworthiness of the results obtained. Also in this sense, the results obtained have been verified with others from satellite radar observation systems, incorporating as well in this study the implications that the joint use of radar technologies and GNSS will have for the future of monitoring deformations in the Earth���s crust.

Design of scour Protection Systems in Offshore Wind Farms

Scour compromises the operation of offshore facilities. This article describes the results of an investigation aimed at the analysis of different methods used in the scour protection systems design at offshore wind farms. The study is focused on transitional waters, where monopile foundations present medium or large diameters. Using the experience of offshore wind farms currently installed, a new design formula is proposed. All of this with the aim of improving a preliminary design of scour protection systems considering maritime parameters

Exploring the origins of topological frustration: Design of a minimally frustrated model of fragment B of protein A

Topological frustration in an energetically unfrustrated off-lattice model of the helical protein fragment B of protein A from Staphylococcus aureus was investigated. This G��-type model exhibited thermodynamic and kinetic signatures of a well-designed two-state folder with concurrent collapse and folding transitions and single exponential kinetics at the transition temperature. Topological frustration is determined in the absence of energetic frustration by the distribution of Fersht �� values. Topologically unfrustrated systems present a unimodal distribution sharply peaked at intermediate ��, whereas highly frustrated systems display a bimodal distribution peaked at low and high �� values. The distribution of �� values in protein A was determined both thermodynamically and kinetically. Both methods yielded a unimodal distribution centered at �� = 0.3 with tails extending to low and high �� values, indicating the presence of a small amount of topological frustration. The contacts with high �� values were located in the turn regions between helices I and II and II and III, intimating that these hairpins are in large part required in the transition state. Our results are in good agreement with all-atom simulations of protein A, as well as lattice simulations of a three- letter code 27-mer (which can be compared with a 60-residue helical protein). The relatively broad unimodal distribution of �� values obtained from the all-atom simulations and that from the minimalist model for the same native fold suggest that the structure of the transition state ensemble is determined mostly by the protein topology and not energetic frustration.

Homogeneous immunoconjugates for boron neutron-capture therapy: Design, synthesis, and preliminary characterization

The application of immunoprotein-based targeting strategies to the boron neutron-capture therapy of cancer poses an exceptional challenge, because viable boron neutron-capture therapy by this method will require the efficient delivery of 103 boron-10 atoms by each antigen-binding protein. Our recent investigations in this area have been focused on the development of efficient methods for the assembly of homogeneous immunoprotein conjugates containing the requisite boron load. In this regard, engineered immunoproteins fitted with unique, exposed cysteine residues provide attractive vehicles for site-specific modification. Additionally, homogeneous oligomeric boron-rich phosphodiesters (oligophosphates) have been identified as promising conjugation reagents. The coupling of two such boron-rich oligophosphates to sulfhydryls introduced to the CH2 domain of a chimeric IgG3 has been demonstrated. The resulting boron-rich immunoconjugates are formed efficiently, are readily purified, and have promising in vitro and in vivo characteristics. Encouragingly, these studies showed subtle differences in the properties of the conjugates derived from the two oligophosphate molecules studied, providing a basis for the application of rational design to future work. Such subtle details would not have been as readily discernible in heterogeneous conjugates, thus validating the rigorous experimental design employed here.

The role of the social environment in non-suicidal self-injury among LGBTQ youth: A mixed methods study

Non-suicidal self-injury (NSSI), such as cutting and burning, is a widespread social problem among lesbian, gay, bisexual, transgender, queer, and questioning (LGBTQ) youth. Extant research indicates that this population is more than twice as likely to engage in NSSI than heterosexual and cisgender (non-transgender) youth. Despite the scope of this social problem, it remains relatively unexamined in the literature. Research on other risk behaviors among LGBTQ youth indicates that experiencing homophobia and transphobia in key social contexts such as families, schools, and peer relationships contributes to health disparities among this group. Consequently, the aims of this study were to examine: (1) the relationship between LGBTQ youth's social environments and their NSSI behavior, and (2) whether/how specific aspects of the social environment contribute to an understanding of NSSI among LGBTQ youth. This study was conducted using an exploratory, sequential mixed methods design with two phases. The first phase of the study involved analysis of transcripts from interviews conducted with 44 LGBTQ youth recruited from a community-based organization. In this phase, five qualitative themes were identified: (1) Violence; (2) Misconceptions, Stigma, and Shame; (3) Negotiating LGBTQ Identity; (4) Invisibility and Isolation; and (5) Peer Relationships. Results from the qualitative phase were used to identify key variables and specify statistical models in the second, quantitative, phase of the study, using secondary data from a survey of 252 LGBTQ youth. The qualitative phase revealed how LGBTQ youth, themselves, described the role of the social environment in their NSSI behavior, while the quantitative phase was used to determine whether the qualitative findings could be used to predict engagement in NSSI among a larger sample of LGBTQ youth. The quantitative analyses found that certain social-environmental factors such as experiencing physical abuse at home, feeling unsafe at school, and greater openness about sexual orientation significantly predicted the likelihood of engaging in NSSI among LGBTQ youth. Furthermore, depression partially mediated the relationships between family physical abuse and NSSI and feeling unsafe at school and NSSI. The qualitative and quantitative results were compared in the interpretation phase to explore areas of convergence and incongruence. Overall, this study's findings indicate that social-environmental factors are salient to understanding NSSI among LGBTQ youth. The particular social contexts in which LGBTQ youth live significantly influence their engagement in this risk behavior. These findings can inform the development of culturally relevant NSSI interventions that address the social realities of LGBTQ youth's lives.

Stability of a Novel Intraocular Lens Design: Comparison of Two Trifocal Lenses

PURPOSE: To compare visual outcomes, rotational stability, and centration in a randomized controlled trial in patients undergoing cataract surgery who were bilaterally implanted with two different trifocal intraocular lenses (IOLs) with a similar optical zone but different haptic shape. METHODS: Twenty-one patients (42 eyes) with cataract and less than 1.50 D of corneal astigmatism underwent implantation of one FineVision/MicoF IOL in one eye and one POD FineVision IOL in the contralateral eye (PhysIOL, Li��ge, Belgium) at IOA Madrid Innova Ocular, Madrid, Spain. IOL allocation was random. Outcome measures, all evaluated 3 months postoperatively, included monocular and binocular uncorrected distance (UDVA), corrected distance (CDVA), distance-corrected intermediate (DCIVA), and near (DCNVA) visual acuity (at 80, 40, and 25 cm) under photopic conditions, refraction, IOL centration, haptic rotation, dysphotopsia, objective quality of vision and aberration quantification, patient satisfaction, and spectacle independence. RESULTS: Three months postoperatively, mean monocular UDVA, CDVA, DCIVA, and DCNVA (40 cm) under photopic conditions were 0.04 �� 0.07, 0.01 �� 0.04, 0.15 �� 0.11, and 0.16 �� 0.08 logMAR for the eyes implanted with the POD FineVision IOL and 0.03 �� 0.05, 0.01 �� 0.02, 0.17 �� 0.12, and 0.14 �� 0.08 logMAR for those receiving the FineVision/MicroF IOL. Moreover, the POD FineVision IOL showed similar centration (P > .05) and better rotational stability (P < .05) than the FineVision/MicroF IOL. Regarding halos, there was a minimal but statistically significant difference, obtaining better results with FineVision/MicroF. Full spectacle independence was reported by all patients. CONCLUSIONS: This study revealed similar visual outcomes for both trifocal IOLs under test (POD FineVision and FineVision/MicroF). However, the POD FineVision IOL showed better rotational stability, as afforded by its design.

What We Are Learning About the Diverse Backgrounds of Academic Library Users: An Overview of Research Designs and Methods in Information Behaviour Studies

Academic libraries increasingly serve a more diverse population of users not only in regard to race and ethnicity, but also to age, gender, language, sexual orientation, and national and cultural backgrounds. This papers reports the findings of the study that explored information behaviour research as a potential source of information about diversity of academic library users and examined the relationship between the use of different research designs and data collection methods and the information gathered about users��� diverse backgrounds. The study found that information behaviour research offers limited insight into the diversity of academic library users. The choice of a research design was not critical but the use of multiple data collection played a role in gathering information about culturally diverse users.