Concepts and methods for efficient decentralized learning in federated settings

Deep Neural Networks (DNNs) have revolutionized a wide range of applications beyond traditional machine learning and artificial intelligence fields, e.g., computer vision, healthcare, natural language processing and others. At the same time, edge devices have become central in our society, generating an unprecedented amount of data which could be used to train data-hungry models such as DNNs. However, the potentially sensitive or confidential nature of gathered data poses privacy concerns when storing and processing them in centralized locations. To this purpose, decentralized learning decouples model training from the need of directly accessing raw data, by alternating on-device training and periodic communications. The ability of distilling knowledge from decentralized data, however, comes at the cost of facing more challenging learning settings, such as coping with heterogeneous hardware and network connectivity, statistical diversity of data, and ensuring verifiable privacy guarantees. This Thesis proposes an extensive overview of decentralized learning literature, including a novel taxonomy and a detailed description of the most relevant system-level contributions in the related literature for privacy, communication efficiency, data and system heterogeneity, and poisoning defense. Next, this Thesis presents the design of an original solution to tackle communication efficiency and system heterogeneity, and empirically evaluates it on federated settings. For communication efficiency, an original method, specifically designed for Convolutional Neural Networks, is also described and evaluated against the state-of-the-art. Furthermore, this Thesis provides an in-depth review of recently proposed methods to tackle the performance degradation introduced by data heterogeneity, followed by empirical evaluations on challenging data distributions, highlighting strengths and possible weaknesses of the considered solutions. Finally, this Thesis presents a novel perspective on the usage of Knowledge Distillation as a mean for optimizing decentralized learning systems in settings characterized by data heterogeneity or system heterogeneity. Our vision on relevant future research directions close the manuscript.

Two stroke cycle, novel combustion concepts and electrification for a new generation of internal combustion engines

The pursuit of decarbonization and increased efficiency in internal combustion engines (ICE) is crucial for reducing pollution in the mobility sector. While electrification is a long-term goal, ICE still has a role to play if coupled with innovative technologies. This research project explores various solutions to enhance ICE efficiency and reduce emissions, including Low Temperature Combustion (LTC), Dual fuel combustion with diesel and natural gas, and hydrogen integration. LTC methods like Dual fuel and Reactivity Controlled Compression Ignition (RCCI) show promise in lowering emissions such as NOx, soot, and CO2. Dual fuel Diesel-Natural Gas with hydrogen addition demonstrates improved efficiency, especially at low loads. RCCI Diesel-Gasoline engines offer increased Brake Thermal Efficiency (BTE) compared to standard diesel engines while reducing specific NOx emissions. The study compares 2-Stroke and 4-Stroke engine layouts, optimizing scavenging systems for both aircraft and vehicle applications. CFD analysis enhances specific power output while addressing injection challenges to prevent exhaust short circuits. Additionally, piston bowl shape optimization in Diesel engines running on Dual fuel (Diesel-Biogas) aims to reduce NOx emissions and enhance thermal efficiency. Unconventional 2-Stroke architectures, such as reverse loop scavenged with valves for high-performance cars, opposed piston engines for electricity generation, and small loop scavenged engines for scooters, are also explored. These innovations, alongside ultra-lean hydrogen combustion, offer diverse pathways toward achieving climate neutrality in the transport sector.

Para uma pedagogia das literacias: das conceções e práticas docentes aos conceitos e competências discentes. Um estudo da aula de língua portuguesa no 2º ciclo do ensino básico

Tese de Doutoramento em Ciências da Educação (Especialidade em Literacias e Ensino do Português)

Why Mathematics is essential in Biomedical Sciences degree?

Improvement of mathematical education and motivation of students in the mathematics" area is needed. What can be done? We introduce some ideas to generate the student"s interest for mathematics, because they often present difficulties in appreciating the relevance of mathematics and its role in the health sciences. We consider that a cornerstone in the strategy to attract the students" interest is linking the mathematics with real biomedical situations. We proceed in the following manner: We first present a real biomedical situation to produce interest and to generate curiosity. Second, we ask thought-provoking questions to students as: Which is the biomedical problem presented? Which is my knowledge on this situation? What could I do to solve this biomedical situation? Do I need some new mathematical concepts and procedures? Thereupon, the teacher explains the mathematical concepts necessary to solve the case presented, providing definitions, properties and tools for graphical display and/or mathematical calculations. In this learning methodology, ICTs were cornerstones for reaching the proposed competences. Furthermore, ICTs can also be used in the evaluative task in its two possible aspects: formative and for obtaining a qualification. Comments from students about this new mathematics teaching method indicate that the use of real biomedical case studies kept the lessons in mathematics interesting.

Hållpunkter för lärande : småbarns möten

Developed from human activities, mathematical knowledge is bound to the world and cultures that men and women experience. One can say that mathematics is rooted in humans’ everyday life, an environment where people reach agreement regarding certain “laws” and principles in mathematics. Through interaction with worldly phenomena and people, children will always gain experience that they can then in turn use to understand future situations. Consequently, the environment in which a child grows up plays an important role in what that child experiences and what possibilities for learning that child has. Variation theory, a branch of phenomenographical research, defines human learning as changes in understanding and acting towards a specific phenomenon. Variation theory implies a focus on that which it is possible to learn in a specific learning situation, since only a limited number of critical aspects of a phenomenon can be simultaneously discerned and focused on. The aim of this study is to discern how toddlers experience and learn mathematics in a daycare environment. The study focuses on what toddlers experience, how their learning experience is formed, and how toddlers use their understanding to master their environment. Twenty-three children were observed videographically during everyday activities. The videographic methodology aims to describe and interpret human actions in natural settings. The children are aged from 1 year, 1 month to 3 years, 9 months. Descriptions of the toddlers’ actions and communication with other children and adults are analyzed phenomenographically in order to discover how the children come to understand the different aspects of mathematics they encounter. The study’s analysis reveals that toddlers encounter various mathematical concepts, similarities and differences, and the relationship between parts and whole. Children form their understanding of such aspects in interaction with other children and adults in their everyday life. The results also show that for a certain type of learning to occur, some critical conditions must exist. Variation, simultaneity, reasonableness and fixed points are critical conditions of learning that appear to be important for toddlers’ learning. These four critical conditions are integral parts of the learning process. How children understand mathematics influences how they use mathematics as a tool to master their surrounding world. The results of the study’s analysis of how children use their understanding of mathematics shows that children use mathematics to uphold societal rules, to describe their surrounding world, and as a tool for problem solving. Accordingly, mathematics can be considered a very important phenomenon that children should come into contact with in different ways and which needs to be recognized as a necessary part of children’s everyday life. Adults working with young children play an important role in setting perimeters for children’s experiences and possibilities to explore mathematical concepts and phenomena. Therefore, this study is significant as regards understanding how children learn mathematics through everyday activities.

Einige Ergebnisse von vergleichenden Untersuchungen in England und Deutschland zum Lehren und Lernen von Mathematik in Realitätsbezügen

In der Arbeit werden einige Resultate von vergleichenden empirischen Untersuchungen zu unterschiedlichen Konzeptionen eines realitätsbezogenen Mathematikunterrichts, wie sie in England und Deutschland häufig vertreten werden, dargestellt. Bei diesen Untersuchungen werden in verschiedenen Fallstudien, die u.a. auch strukturelle Unterschiede zwischen den Bildungssystemen in England und Deutschland und den zugrundeliegenden Erziehungsphilosophien berücksichtigen, Auswirkungen dieser Konzeptionen auf die Einstellung der Lernenden zum Mathematikunterricht, ihr Bild von Mathematik, ihr Verständnis mathematischer Begriffe und Methoden sowie ihre Fähigkeiten zur Anwendung mathematischer Methoden zum Lösen realer Problemaufgaben untersucht. Die hier dargestellten Erhebungen sind Teil eines längerdauernden Kollaborationsprojekts zwischen den Universitäten Exeter und Kassel.

Lecture Notes on Compositional Data Analysis

These notes have been prepared as support to a short course on compositional data analysis. Their aim is to transmit the basic concepts and skills for simple applications, thus setting the premises for more advanced projects

Oralidade, leitura e escrita numa criança com défice cognitivo

RESUMO: Este projecto de intervenção, fundamentado na investigação/acção, teve como objectivo melhorar a oralidade, leitura e escrita funcionais numa aluna com Défice cognitivo moderado e, consequentemente, promover a sua inclusão em contexto escolar, bem como desenvolver nos restantes colegas atitudes de entreajuda, respeito e cooperação. Decorreu de Fevereiro de 2009 até Junho do mesmo ano. “B” é o nome fictício da aluna em estudo que, aquando a nossa intervenção, frequentava o 3º ano do 1º ciclo numa escola pública. A escolha da questão de partida prendeu-se com a emergência de dar resposta à necessidade que os pais, professores e a criança em questão tinham para que esta desenvolvesse competências de leitura, expressão oral e escrita O enquadramento teórico teve como objectivo facilitar a compreensão da intervenção. Para recolher informações sobre a “B” e sobre os contextos em que a mesma estava inserida, utilizámos como suporte metodológico, a pesquisa documental, o teste sociométrico, as entrevistas semi-directivas à professora de turma e à professora de Educação Especial, a observação naturalista e questionários à mãe da aluna. Foi feito um trabalho conjunto com a professora do ensino regular, com a professora de educação especial e com os pais, no sentido de delinear as estratégias/actividades mais benéficas, de modo a dar resposta às competências a desenvolver com a aluna. No fim da nossa intervenção, em Junho de 2009, esta já sabia escrever o seu nome sem modelo, desenvolveu o vocabulário e melhorou a construção frásica oral. Ao seu ritmo, envolveu-se mais nas actividades da sala de aula. Na aquisição de conceitos e competências, estas tiveram de ser muito simples, reais e concretas para que fossem adquiridas e aplicadas. No entanto, ainda tinha dificuldade em concentrar a atenção sem ajuda. No que diz respeito ao desenvolvimento da linguagem, o discurso utilizado pela “B” melhorou significativamente, passando a construir frases simples com linguagem mais perceptiva, apesar de comunicar com frases curtas e com pouca expressividade. ABSTRACT: This intervention project, based on research / action, was aimed to improve speaking, reading and writing skills in a functional student with moderate cognitive deficit, promote her inclusion in the school context and develop mutual help, respect and cooperation in her classmates attitudes. It ran from February until June, 2009."B" is the fictional name of the student in this study that during our intervention, attended the 3rd year of Primary school in a public school. The choice of the starting point had to do with the urgency of answering the parents, teachers and the child needs in what concerns the development of the reading, writing and speaking skills. The theoretical framework was aimed to facilitate understanding of the intervention. To gather information about "B" and the contexts in which she was placed, it was used, as a methodological support, research documents, the sociometric test, the semi-directive interviews to the class teacher and the Special Education teacher, the naturalist observation and the questionnaires to the student’s mother. Team work was done with the class teacher, the Special Education teacher and the parents, to outline the strategies / activities most beneficial, in order to establish the skills to be developed with the student. At the end of our intervention in June 2009, she could already write her name without a model, had developed and improved vocabulary oral sentence construction. At her own pace, she became more involved in the classroom activities. Concepts and skills acquisition had to be very simple, real and concrete to be acquired and applied. However, she still had some difficulty in focusing attention without help. What concerns language development, “B” has improved significantly from the simple sentences in more perceptive language, although she still communicates with short sentences and with little expression.

Objetiva(ação) da medida e contagem do tempo em práticas socioculturais e educativas

This thesis describes and analyzes various processes established and practiced by both groups about the socio-cultural objective (action) the measurement and timing, mobilized some socio-historical practices as the use of the gnômon of the sundial and reading and interpretation of movements celestial constellations in cultural contexts such as indigenous communities and fishermen in the state of Pará, Brazil. The Purpose of the study was to describe and analyze the mobilization of such practices in the socio-historical development of matrices for teaching concepts and skills related to geometric angles, similar triangles, symmetry and proportionality in the training of mathematics teachers. The record of the entire history of investigation into the socio-historical practice, the formative action was based on epistemological assumptions of education ethnomathematics proposed by Vergani (2000, 2007) and Ubiratan D'Ambrosio (1986, 1993, 1996, 2001, 2004) and Alain Bishop conceptions about mathematics enculturation. At the end of the study I present my views on the practices of contributions called socio-cultural and historical for school mathematics, to give meaning to the concept formation and teaching of students, especially the implications of Education Ethnomatematics proposed by Vergani (2000) for training of future teachers of mathematics

Temas político-sociais no ensino da Matemática

Este trabalho teve como objetivo propiciar condições para a aprendizagem de conceitos matemáticos e verificar se o conteúdo Estatística, abordado por meio da análise de tabelas e gráficos, trabalhado em grupos cooperativos, por intermédio da resolução de Problemas Ampliados por Temas Transversais/Político-Sociais, pode contribuir para a transformação do ensino e aprendizagem desse conteúdo e para a formação de seres humanos comprometidos com os aspectos políticos, culturais, sociais e ambientais da sociedade em que vivem.

Padrões fractais: contribuições ao processo de generalização de conteúdos matemáticos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Os Processos de visualização e de representação dos signos matemáticos no contexto didático-pedagógico

Pós-graduação em Educação Matemática - IGCE

Um modelo algébrico para a lógica do muito

Pós-graduação em Filosofia - FFC

Sobre quantificadores: uma formalização do quantificador 'quase sempre'

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Um curso de matemática básica através da resolução de problemas para alunos ingressantes da Universidade Federal do Pampa - campus Alegrete

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)