Mejora del comportamiento térmico de los morteros de cal aditivados y su empleo en la rehabilitación de inmuebles = Improvement of thermal behaviour of additived lime mortars and their use in rehabilitation of buildings

La envolvente de la edificación es la responsable de equilibrar el intercambio energético entre el interior y el exterior, por lo tanto cualquier actuación encaminada a la reducción del consumo energético ha de establecer, como uno de sus objetivos prioritarios, la mejora del comportamiento de la misma. Las edificaciones anteriores a 1940 constituyen la mayor parte de las existentes en áreas rurales y centros urbanos. En ellas, la repercusión de la fachada sobre las transmitancias globales pone de manifiesto la necesidad de intervención. Sin embargo, su elevada inercia térmica y los importantes saltos térmicos característicos de gran parte de España plantean la importancia de que aquélla se efectúe por el exterior. A tal respecto, la falta de disponibilidad de espesor suficiente para implantar sistemas tipo SATE deriva en que, frecuentemente, la única solución viable sea la de aislar por el interior perdiendo con ello la capacidad de acumulación térmica del muro y con el asociado riesgo de condensaciones. La amplia tradición en el empleo de revestimientos, especialmente en base de cal, permiten que éstos sean utilizados no sólo como elemento estético o de protección de la obra de fábrica antigua sino también para la mejora del comportamiento térmico del soporte, si se aprovecha el mecanismo de transmisión térmica por radiación. Éste es el objetivo de la presente Tesis Doctoral en la que se estudia la modificación de las propiedades radiantes de los morteros de revestimiento para la mejora de la eficiencia energética de las construcciones históricas, principalmente las constituidas por muros monolíticos, aunque podría ser de aplicación a otro tipo de construcciones compuestas por diversas capas. Como punto de partida, se estudió y revisó la documentación disponible sobre las investigaciones de las tres áreas científico-tecnológicas que convergen en la Tesis Doctoral: rehabilitación, material y comportamiento térmico, a partir de lo cual se comprobó la inexistencia de estudios similares al objeto de la presente Tesis Doctoral. Complementariamente, se analizaron los revestimientos en lo concerniente a los materiales que los constituyen, la composición de las mezclas y características de cada una de las capas así como al enfoque que, desde el punto de vista térmico, se estimaba más adecuado para la obtención de los objetivos propuestos. Basándonos en dichos análisis, se preseleccionaron ochenta materiales que fueron ensayados en términos de reflectancia y emisividad para elegir cuatro con los que se continuó la investigación. Éstos, junto con la cal elegida para la investigación y el árido marmóreo característico de la última capa de revestimiento, fueron caracterizados térmicamente, de forma pormenorizada, así como química y físicamente. Los fundamentos teóricos y los estudios preliminares desarrollados con distintos materiales, en estado fresco y endurecido, fueron empleados en la dosificación de componentes de las mezclas, en dos proporciones distintas, para el estudio del efecto del agregado. Éstas se ensayaron en estado fresco, para comprobar su adecuación de puesta en obra y prever su VI adherencia al soporte, así como en estado endurecido a 28 y 90 días de curado, para conocer las propiedades que permitieran prever su compatibilidad con aquél y estimar el alcance de la reducción de transferencias térmicas lograda. Además, se estudiaron las características generales de las mezclas que sirvieron para establecer correlaciones entre distintas propiedades y entender los resultados mecánicos, físicos (comportamiento frente al agua) y energéticos. Del estudio conjunto de las distintas propiedades analizadas se propusieron dos mezclas, una blanca y otra coloreada, cuyas características permiten garantizar la compatibilidad con la obra de fábrica antigua, desde el punto de vista físico y mecánico, y preservar la autenticidad de los revestimientos, en cuanto a la técnica de aplicación tradicional en sistemas multicapa. El comportamiento térmico de las mismas, sobre una obra de fábrica de 40 cm de espesor, se estimó, en estado estacionario y pseudo-transitorio, demostrándose reducciones del flujo térmico entre 16-48%, en condiciones de verano, y entre el 6-11%, en invierno, en función de la coloración y de la rugosidad de la superficie, en comparación con el empleo de la mezcla tradicional. Por lo que, se constata la viabilidad de los materiales compuestos propuestos y su adecuación al objetivo de la investigación. VII ABSTRACT The envelope is responsible for balancing the energy exchange between the inside and outside in buildings. For this reason, any action aimed at reducing energy consumption must establish, as one of its key priorities, its improvement. In rural areas and urban centers, most of the constructions were built before 1940. In them, the impact of the façade on the global transmittance highlights the need for intervention. However, its high thermal inertia and fluctuation of temperatures in the majority of Spain bring up that it should be placed outside the insulation. In this regard, the lack of availability of enough thickness to implement systems such as ETICS results in that often the only viable solution is to isolate the interior, losing thereby the wall’s heat storage capacity with the associated risk of condensation. The tradition in the use of renders, especially lime-based, allows us to use them not only as an aesthetic element or to protect the ancient masonry, but also for improved thermal performance of the support by taking advantage of the heat transfer mechanism by radiation. This is the aim of this Doctoral Thesis in which the modification of the radiative properties of lime mortars for renders to improve the energy efficiency of historic buildings, mainly composed of monolithic walls, is studied, although it could be applied to other structures composed of several layers. As a starting point, the available literature in the three scientific-technological areas that converge at the Doctoral Thesis: rehabilitation, material and thermal behaviour, was reviewed, and confirmed the absence of researches similar to this Doctoral Thesis. Additionally, the renders were studied with regard to the materials that constitute them, the composition of the mixtures and the characteristics of each layer, as well as to the approach which, from a thermal point of view, was deemed the most suitable for achieving the objectives sets. Based on thre aforementioned analysis, eighty materials tested in terms of reflectance and emissivity were pre-selected, to choose four with which the research was continued. Common marble sand, used in the last layer of the renders, together with the appointed materials and hydrated lime were characterized thermally, in detail, as well as chemically and physically. The theoretical bases and preliminary studies with different materials, in fresh and hardened state, were used in the dosage of the composition of the mixtures. In order to study their effect they were used in two different proportions, that is, ten mixtures in total. These were tested in their fresh state to evaluate their setting-up suitability and foresee their adhesion to the support, as well as in their hardened state, at 28 and 90 days of curing, to establish the properties which enabled us to anticipate their compatibility with the old masonry walls and estimate the scope of the reduction of heat transfers achieved. In addition, the general characteristics of the mixtures used to establish correlations and to understand the mechanical, physical and energy results were studied. Two mixtures, one white and one colored, were proposed as the result of the different properties analysed, whose characteristics allow the guarantee of mechanical and physical compatibility VIII with the old masonry and preserve the authenticity of the renders. The thermal behavior of both, applied on a masonry wall 40 cm thick, was estimated at a steady and pseudo-transient state, with heat flow reductions between 16-48% during summertime and 6-11% during wintertime, depending on the color and surface roughness, compared to the use of the traditional mixture. So, the viability of the proposed composite materials and their fitness to the aim of the research are established.

Sample Size vs. Bias in Defect Prediction

Most empirical disciplines promote the reuse and sharing of datasets, as it leads to greater possibility of replication. While this is increasingly the case in Empirical Software Engineering, some of the most popular bug-fix datasets are now known to be biased. This raises two significants concerns: first, that sample bias may lead to underperforming prediction models, and second, that the external validity of the studies based on biased datasets may be suspect. This issue has raised considerable consternation in the ESE literature in recent years. However, there is a confounding factor of these datasets that has not been examined carefully: size. Biased datasets are sampling only some of the data that could be sampled, and doing so in a biased fashion; but biased samples could be smaller, or larger. Smaller data sets in general provide less reliable bases for estimating models, and thus could lead to inferior model performance. In this setting, we ask the question, what affects performance more? bias, or size? We conduct a detailed, large-scale meta-analysis, using simulated datasets sampled with bias from a high-quality dataset which is relatively free of bias. Our results suggest that size always matters just as much bias direction, and in fact much more than bias direction when considering information-retrieval measures such as AUC and F-score. This indicates that at least for prediction models, even when dealing with sampling bias, simply finding larger samples can sometimes be sufficient. Our analysis also exposes the complexity of the bias issue, and raises further issues to be explored in the future.

CDAPubMed: a browser extension to retrieve EHR-based biomedical literature

Over the last few decades, the ever-increasing output of scientific publications has led to new challenges to keep up to date with the literature. In the biomedical area, this growth has introduced new requirements for professionals, e.g., physicians, who have to locate the exact papers that they need for their clinical and research work amongst a huge number of publications. Against this backdrop, novel information retrieval methods are even more necessary. While web search engines are widespread in many areas, facilitating access to all kinds of information, additional tools are required to automatically link information retrieved from these engines to specific biomedical applications. In the case of clinical environments, this also means considering aspects such as patient data security and confidentiality or structured contents, e.g., electronic health records (EHRs). In this scenario, we have developed a new tool to facilitate query building to retrieve scientific literature related to EHRs. Results: We have developed CDAPubMed, an open-source web browser extension to integrate EHR features in biomedical literature retrieval approaches. Clinical users can use CDAPubMed to: (i) load patient clinical documents, i.e., EHRs based on the Health Level 7-Clinical Document Architecture Standard (HL7-CDA), (ii) identify relevant terms for scientific literature search in these documents, i.e., Medical Subject Headings (MeSH), automatically driven by the CDAPubMed configuration, which advanced users can optimize to adapt to each specific situation, and (iii) generate and launch literature search queries to a major search engine, i.e., PubMed, to retrieve citations related to the EHR under examination. Conclusions: CDAPubMed is a platform-independent tool designed to facilitate literature searching using keywords contained in specific EHRs. CDAPubMed is visually integrated, as an extension of a widespread web browser, within the standard PubMed interface. It has been tested on a public dataset of HL7-CDA documents, returning significantly fewer citations since queries are focused on characteristics identified within the EHR. For instance, compared with more than 200,000 citations retrieved by breast neoplasm, fewer than ten citations were retrieved when ten patient features were added using CDAPubMed. This is an open source tool that can be freely used for non-profit purposes and integrated with other existing systems.

Temporal task allocation in periodic environments. An approach based on synchronization

In this paper, we study a robot swarm that has to perform task allocation in an environment that features periodic properties. In this environment, tasks appear in different areas following periodic temporal patterns. The swarm has to reallocate its workforce periodically, performing a temporal task allocation that must be synchronized with the environment to be effective. We tackle temporal task allocation using methods and concepts that we borrow from the signal processing literature. In particular, we propose a distributed temporal task allocation algorithm that synchronizes robots of the swarm with the environment and with each other. In this algorithm, robots use only local information and a simple visual communication protocol based on light blinking. Our results show that a robot swarm that uses the proposed temporal task allocation algorithm performs considerably more tasks than a swarm that uses a greedy algorithm.

A tool assisting teachers in automating the assessment of programming assignments

Automating the assessment of programming assignments brings benefits for both students and teachers, since it helps the formers to gain a timely feedback and releases the latter from tedious tasks. The related literature in the domain has usually focused on the assessment process and the tools required for it, proposing libraries and systems that teachers can use in this process. However, few of them have work rowards reducing the effort and time teacher require to properly set up new assessente processes. This paper describes our experience with the analysis and design of a new tool to support teachers in visually developing automatic grades of programming assignments, introducing the underlying concepts and technologies and presenting the system architecture.

A real case of a cognitive multiplayer game: design and development of the iOS client in Swift and its cloud architecture

as tecnologías emergentes como el cloud computing y los dispositivos móviles están creando una oportunidad sin precedentes para mejorar el sistema educativo, permitiendo tanto a los educadores personalizar y mejorar la experiencia de aprendizaje, como facilitar a los estudiantes que adquieran conocimientos sin importar dónde estén. Por otra parte, a través de técnicas de gamificacion será posible promover y motivar a los estudiantes a que aprendan materias arduas haciendo que la experiencia sea más motivadora. Los juegos móviles pueden ser el camino correcto para dar soporte a esta experiencia de aprendizaje mejorada. Este proyecto integra el diseño y desarrollo de una arquitectura en la nube altamente escalable y con alto rendimiento, así como el propio cliente de iOS, para dar soporte a una nueva version de Temporis, un juego móvil multijugador orientado a reordenar eventos históricos en una línea temporal (e.j. historia, arte, deportes, entretenimiento y literatura). Temporis actualmente está disponible en Google Play. Esta memoria describe el desarrollo de la nueva versión de Temporis (Temporis v.2.0) proporcionando detalles acerca de la mejora y adaptación basados en el Temporis original. En particular se describe el nuevo backend hecho en Go sobre Google App Engine creado para soportar miles de usuarios, asó como otras características por ejemplo como conseguir enviar noticaciones push desde la propia plataforma. Por último, el cliente de iOS en Temporis v.2.0 se ha desarrollado utilizando las últimas y más relevantes tecnologías, prestando especial atención a Swift (el lenguaje de programación nuevo de Apple, que es seguro y rápido), el Paradigma Funcional Reactivo (que ayuda a construir aplicaciones altamente interactivas además de a minimizar errores) y la arquitectura VIPER (una arquitectura que sigue los principios SOLID, se centra en la separación de asuntos y favorece la reutilización de código en otras plataformas). ABSTRACT Emerging technologies such as cloud computing and mobile devices are creating an unprecedented opportunity for enhancing the educational system, letting both educators customize and improve the learning experience, and students acquire knowledge regardless of where they are. Moreover, through gamification techniques it would be possible to encourage and motivate students to learn arduous subjects by making the experience more motivating. Mobile games can be a perfect vehicle to support this enhanced learning experience. This project integrates the design and development of a highly scalable and performant cloud architecture, as well as the iOS client that uses it, in order to provide support to a new version of Temporis, a mobile multiplayer game focused on ordering time-based (e.g. history, art, sports, entertainment and literature) in a timeline that currently is available on Google Play. This work describes the development of the new Temporis version (Temporis v.2.0), providing details about improvements and details on the adaptation of the original Temporis. In particular, the new Google App Engine backend is described, which was created to support thousand of users developed in Go language are provided, in addition to other features like how to achieve push notications in this platform. Finally, the mobile iOS client developed using the latest and more relevant technologies is explained paying special attention to Swift (Apple's new programming language, that is safe and fast), the Functional Reactive Paradigm (that helps building highly interactive apps while minimizing bugs) and the VIPER architecture (a SOLID architecture that enforces separation of concerns and makes it easy to reuse code for other platforms).