Contributo para a melhoria do desempenho térmico das paredes de taipa

O uso da construção em terra remonta ao início da nossa civilização. Nas regiões do Alentejo e do Algarve existe ainda um grande número de edifícios com paredes em taipa, mas esta tecnologia tem vindo a cair em desuso desde meados do século passado. A construção em terra é altamente sustentável, já que a terra per si é um material 100% reutilizável e pode ser facilmente encontrado em quase todos os lugares do mundo. Os edifícios com paredes em taipa apresentam uma elevada inércia térmica o que, dadas as características climáticas de Portugal, beneficia o seu comportamento térmico. No entanto, seria desejável que a condutibilidade térmica da taipa fosse menor. As preocupações ambientais relativas ao consumo energético, associado ao conforto na habitação, e ao fabrico, transporte e aplicação dos materiais utilizados na construção, levou-nos a procurar novas soluções de tipologias construtivas em terra. Atendendo a estes aspetos e à melhoria da eficiência energética das habitações, neste trabalho são apresentados os resultados dos ensaios realizados em laboratório sobre novas soluções de construção em terra. O local selecionado para a recolha de amostras de terra foi Serpa. Foi feita a caracterização geotécnica do material terra e preparadas diversas composições com a incorporação de argila expandida e de regranulado de cortiça expandida. A argila expandida e o regranulado de cortiça expandida também foram escolhidos por serem isolantes térmicos produzidos a partir de matérias primas disponíveis nas regiões do Alentejo e do Algarve, regiões do nosso país com maior aptência para o uso da taipa. De maneira a caracterizar as diferentes composições sob o ponto de vista mecânico e do desempenho térmico, foram fabricados cubos com 10 cm de aresta e ensaiados de modo a se calcular a sua resistência à compressão e a sua condutibilidade térmica. Os resultados obtidos mostraram que a utilização deste tipo de tipologias construtivas em terra com a incorporação de argila expandida e de regranulado de cortiça expandida permite aumentar o seu desempenho, fazendo que seja possível adaptar esta tipologia às necessidades dos dias de hoje, nomeadamente às exigências estabelecidas pelo Regulamento das Características de Comportamento Térmico dos Edifícios (RCCTE). Os resultados desta investigação têm aplicabilidade, com as devidas adaptações, tanto em construções em taipa como em construções em adobe

The footloose entrepreneur model with a finite number of equidistant regions

We study the Footloose Entrepreneur model with a finite number of equidistant regions, focusing on the analysis of stability of agglomeration, total dispersion, and boundary dispersion. As the number of regions increases, there is more tendency for agglomeration and less tendency for dispersion. As it tends to infinity, agglomeration always becomes stable while dispersion always becomes unstable. These results are robust to any composition of the global workforce and its dependence on the number of regions. Numerical evidence suggests that boundary dispersion is never stable. We introduce exogenous regional heterogeneity and obtain a general condition for stability of agglomeration.info:eu-repo/semantics/acceptedVersio

Sharp Hessian estimates for fully nonlinear elliptic equations under relaxed convexity assumptions, oblique boundary conditions and applications

In this work we derive global estimates for viscosity solutions to fully nonlinear elliptic equations under relaxed structural assumptions on the governing operator which are weaker than convexity and oblique boundary conditions and under suitable assumptions on the dat. Our approach makes use of geometric tangential methods, which consists of importing "fine regularity estimates" from a limiting profile, i.e., the Recession operator, associated with the original second order one via compactness and stability procedures. As a result, we devote a special attention to the borderline scenario. In such a setting, we prove that solutions enjoy BMO type estimates for their second derivatives. In the end, as another application of our findings, we obtain Hessian estimates to obstacle type problems under oblique boundary conditions and no convexity assumptions, which may have their own mathematical interest. A density result in a suitable class of viscosity solutions will be also addressed

Agglomeration patterns in a multi-regional economy without income effects

We study the long-run spatial distribution of industry using a multi-region core–periphery model with quasi-linear log utility Pflüger (Reg Sci Urban Econ 34:565–573, 2004). We show that a distribution in which industry is evenly dispersed among some of the regions, while the other regions have no industry, cannot be stable. A spatial distribution where industry is evenly distributed among all regions except one can be stable, but only if that region is significantly more industrialized than the other regions. When trade costs decrease, the type of transition from dispersion to agglomeration depends on the fraction of workers that are mobile. If this fraction is low, the transition from dispersion to agglomeration is catastrophic once dispersion becomes unstable. If it is high, there is a discontinuous jump to partial agglomeration in one region and then a smooth transition until full agglomeration. Finally, we find that mobile workers benefit from more agglomerated spatial distributions, whereas immobile workers prefer more dispersed distributions. The economy as a whole shows a tendency towards overagglomeration for intermediate levels of trade costs.info:eu-repo/semantics/acceptedVersio

Economic geography meets hotelling: a home-sweet-home effect

We propose a 2-region core-periphery model where all agents are inter-regionally mobile and have Hotelling-type heterogeneous preferences for location. The utility penalty from residing in a location that is not the preferred one generates the only dispersive force of the model: the home-sweet-home effect. Different distributions of preferences for location induce different spatial distributions in the long-run depending on the short-run general equilibrium economic geography model that is considered. We study the effect of two of those: the linear and the logit home-sweet-home effects.info:eu-repo/semantics/publishedVersio

Remote Experimentation supported by Learning Analytics and Recommender Systems

This paper proposes a process based on learning analytics and recommender systems targeted at making suggestions to students about their remote laboratories activities and providing insights to all stakeholders taking part in the learning process. To apply the process, a log with requests and responses of remote experiments from the VISIR project were analyzed. A request is the setup of the experiment including the assembled circuits and the configurations of the measuring equipment. In turn, a response is a message provided by the measurement server indicating measures or an error when it is not possible to execute the experiment. Along the two phases of analysis, the log was analyzed and summarized in order to provide insights about students' experiments. In addition, there is a recommendation service responsible for analyzing the requests thus returning, in case of error, precise information about the assembly of circuits or configurations. The evaluation of the process is consistent in what regards its ability to afford recommendations to the students as they carry out the experiments. Moreover, the summarized information intends to offer teachers means to better understand and develop strategies to scaffold students' learning.info:eu-repo/semantics/publishedVersio

Remote Experimentation supported by Learning Analytics and Recommender Systems

This paper proposes a process based on learning analytics and recommender systems targeted at making suggestions to students about their remote laboratories activities and providing insights to all stakeholders taking part in the learning process. To apply the process, a log with requests and responses of remote experiments from the VISIR project were analyzed. A request is the setup of the experiment including the assembled circuits and the configurations of the measuring equipment. In turn, a response is a message provided by the measurement server indicating measures or an error when it is not possible to execute the experiment. Along the two phases of analysis, the log was analyzed and summarized in order to provide insights about students' experiments. In addition, there is a recommendation service responsible for analyzing the requests thus returning, in case of error, precise information about the assembly of circuits or configurations. The evaluation of the process is consistent in what regards its ability to afford recommendations to the students as they carry out the experiments. Moreover, the summarized information intends to offer teachers means to better understand and develop strategies to scaffold students' learning.info:eu-repo/semantics/publishedVersio

Learning Analytics and Recommender Systems toward Remote Experimentation

This paper presents a process based on learning analytics and recom- mender systems to provide suggestions to students about remote laboratories ac- tivities in order to scaffold their performance. For this purpose, the records of remote experiments from the VISIR project were analyzed taking into account one of its installations. Each record is composed of requests containing the as- sembled circuits and the configurations of the measuring equipment, as well as the response provided by the measurement server that evaluates whether a par- ticular request can be performed or not. With the log analysis, it was possible to obtain information in order to determine some initial statistics and provide clues about the student’s behavior during the experiments. Using the concept of rec- ommendation, a service is proposed through request analysis and returns to the students more precise information about possible mistakes in the assembly of circuits or configurations. The process as a whole proves consistent in what re- gards its ability to provide suggestions to the students as they conduct the exper- iments. Furthermore, with the log, relevant information can be offered to teach- ers, thus assisting them in developing strategies to positively impact student’s learning.info:eu-repo/semantics/publishedVersio