Devido ao grande número de otimizações fornecidas pelos compiladores modernos e à ampla possibilidade de ordenação dessas transformações, uma eficiente Exploração do Espaço de Projeto (DSE) se faz necessária para procurar a melhor sequência de otimização de uma determinada função ou fragmento de código. Como esta exploração é uma tarefa complexa e dispendiosa, apresentamos uma nova abordagem de DSE capaz de reduzir esse tempo de exploração e selecionar sequências de otimização que melhoraram o desempenho dos códigos transformados. Nossa abordagem utiliza um conjunto de funções de referência, para as quais uma representação simbólica do código (DNA) e a melhor sequência de otimização são conhecidas. O DSE de novas funções é baseado em uma abordagem de agrupamento aplicado sobre o código DNA que identifica similaridades entre funções. O agrupamento utiliza três técnicas para a mineração de dados: distância de compressão normalizada, algoritmo de reconstrução de árvores filogenéticas (Neighbor Joining) e identificação de grupos por ambiguidade. As otimizações das funções de referência identificadas como similares formam o espaço que é explorado para encontrar a melhor sequência para a nova função. O DSE pode utilizar o conjunto reduzido de otimizações de duas formas: como o espaço de projeto ou como a configuração inicial do algoritmo. Em ambos os casos, a adoção de uma pré-seleção baseada no agrupamento permite o uso de algoritmos de busca simples e rápidos. Os resultados experimentais revelam que a nova abordagem resulta numa redução significativa no tempo total de exploração, ao mesmo tempo que alcança um desempenho próximo ao obtido através de uma busca mais extensa e dispendiosa baseada em algoritmos genéticos. / Due to the large number of optimizations provided in modern compilers and to compiler optimization specific opportunities, a Design Space Exploration (DSE) is necessary to search for the best sequence of compiler optimizations for a given code fragment (e.g., function). As this exploration is a complex and time consuming task, we present new DSE strategies to reduce the exploration time and still select optimization sequences able to improve the performance of each function. The DSE is based on a clustering approach which groups functions with similarities and then explore the reduced search space provided by the optimizations previously suggested for the functions in each group. The identification of similarities between functions uses a data mining method which is applied to a symbolic representation of the source code. The DSE strategies uses the reduced optimizations set identified by clustering in two ways: as the design space or as the initial configuration of the algorithm. In both ways, the adoption of a pre-selection based on clustering allows the use of simple and fast DSE algorithms. Several experiments for evaluating the effectiveness of the proposed approach address the exploration of compiler optimization sequences. Besides, we investigate the impact of each technique or component employed in the selection process. Experimental results reveal that the use of our new clustering-based DSE approach achieved a significant reduction on the total exploration time of the search space at the same time that obtained performance speedups close to a traditional genetic algorithmbased approach.

Sistemas para análise de imagens partem da premissa de que o conjunto de dados sob investigação está corretamente representado por características. Entretanto, definir quais características representam apropriadamente um conjunto de dados é uma tarefa desafiadora e exaustiva. Grande parte das técnicas de descrição existentes na literatura, especialmente quando os dados têm alta dimensionalidade, são baseadas puramente em medidas estatísticas ou abordagens baseadas em inteligência artificial, e normalmente são caixas-pretas para os usuários. A abordagem proposta nesta dissertação busca abrir esta caixa-preta por meio de representações visuais criadas pela técnica Multidimensional Classical Scaling, permitindo que usuários capturem interativamente a essência sobre a representatividade das características computadas de diferentes descritores. A abordagem é avaliada sobre seis conjuntos de imagens que contém texturas, imagens médicas e cenas naturais. Os experimentos mostram que, conforme a combinação de um conjunto de características melhora a qualidade da representação visual, a acurácia de classificação também melhora. A qualidade das representações é medida pelo índice da silhueta, superando problemas relacionados com a subjetividade de conclusões baseadas puramente em análise visual. Além disso, a capacidade de exploração visual do conjunto sob análise permite que usuários investiguem um dos maiores desafios em classificação de dados: a presença de variação intra-classe. Os resultados sugerem fortemente que esta abordagem pode ser empregada com sucesso como um guia para auxiliar especialistas a explorar, refinar e definir as características que representam apropriadamente um conjunto de imagens / Image analysis systems rely on the fact that the dataset under investigation is correctly represented by features. However, defining a set of features that properly represents a dataset is still a challenging and, in most cases, an exhausting task. Most of the available techniques, especially when a large number of features is considered, are based on purely quantitative statistical measures or approaches based on artificial intelligence, and normally are black-boxes to the user. The approach proposed here seeks to open this black-box by means of visual representations via Multidimensional Classical Scaling projection technique, enabling users to get insight about the meaning and representativeness of the features computed from different feature extraction algorithms and sets of parameters. This approach is evaluated over six image datasets that contains textures, medical images and outdoor scenes. The results show that, as the combination of sets of features and changes in parameters improves the quality of the visual representation, the accuracy of the classification for the computed features also improves. In order to reduce this subjectiveness, a measure called silhouette index, which was originally proposed to evaluate results of clustering algorithms, is employed. Moreover, the visual exploration of datasets under analysis enable users to investigate one of the greatest challenges in data classification: the presence of intra-class variation. The results strongly suggest that our approach can be successfully employed as a guidance to defining and understanding a set of features that properly represents an image dataset

La spécificité de cette recherche réside dans sa réalisation par la validation des acquis de l'expérience professionnelle (VAE), en simultanée avec le développement des approches en vue de la patrimonialisation des sites technologiques liés à l'exploration spatiale, conduits par l’auteure au titre de ses fonctions à l'UNESCO, en tant que le responsable de l'Initiative thématique « Astronomie et patrimoine mondial». Cette recherche retrace et analyse les enjeux de la patrimonialisation des sites liés à l'exploration spatiale sous un prisme d'une obligatoire corrélation entre le patrimoine terrestre de l'Espace et le patrimoine extra-atmosphérique.La patrimonialisation des sites technologiques liés à l'exploration spatiale est une étape charnière d'un processus de reconnaissance du patrimoine de l'Espace. Cette recherche positionne deux contextes. L'un est lié à la mise en place d'un instrument normatif international qui délimite le périmètre du patrimoine mondial appartenant à l'Humanité tout entière. L'autre est celui lié au commencement de l'Ère Spatiale et à l'exploration de l'Espace. Ce dernier donne naissance à des sites qu'illustrent une exceptionnelle prouesse technologique et le génie créateur humain. La patrimonialisation de ces sites est étudiée dans une approche de création de passerelles entre les deux contextes susmentionnés qui se sont développés parallèlement, sans jamais se croiser. Ce travail de restitution contextuelle s’appuie sur les témoignages des personnes clefs qui ont contribués à la mise en oeuvre de la Convention du patrimoine mondial, et notamment à l'avancement de la reconnaissance des valeurs associées à la science. La problématique de cette recherche s'inscrit dans le cadre des études interdisciplinaires dans le domaine de science, technologie, patrimoine et logiques de participation. Ce projet constitue un apport aux axes de recherches du Laboratoire HT2S Histoire des Technosciences en Société du Conservatoire National des Arts et Métiers (CNAM). / The specificity of this research resides in its realisation by the validation of the acquired professional experience (VAE), simultaneously with the development of the approaches for the patrimonialisation of the technological sites related to space exploration, led by the author in her role at UNESCO as responsible for the Thematic Initiative "Astronomy and World Heritage". This research retraces and analyses the implementation of the issues of patrimonialisation of heritage-related sites linked to space exploration under the prism of an obligatory correlation between space heritage on Earth and outer-space heritage.The patrimonialisation of technological sites related to space exploration is a milestone in the process of recognition of space heritage. This research positions two contexts. One is linked to the establishment of an international normative instrument that delimits the World Heritage perimeter belonging to the whole of Humanity. The other is the one related to the beginning of the Space Age and space exploration. The latter gives rise to sites that illustrate an exceptional technological feat and human creative genius. The patrimonialisation of these sites is studied with an approach to create bridges between the two aforementioned contexts that have developed in parallel, without ever crossing. This work of contextual restitution is based on the testimony of key persons who contributed to the implementation of the World Heritage Convention, and in particular to the advancement of the recognition of the values associated with science. The research problem is part of the interdisciplinary studies in the field of science, technology, heritage and logics of participation. This project is a contribution to the research themes of the HT2S Laboratory on History of Technosciences in Society of the National Conservatory of Arts and Crafts (CNAM).

Este trabalho propõe uma nova abordagem para o desenvolvimento de sistemas embarcados, através da combinação da abstração e propriedades de verificação de modelos da linguagem declarativa Alloy com a ampla aceitação de Java na indústria. A abordagem surge no contexto de que a automação de software no domínio embarcado tornou-se extremamente necessária, uma vez que atualmente a maior parte do tempo de desenvolvimento é gasta no projeto de software de produtos tão restritos em termos de recursos. As ferramentas de automação de software embarcado devem atender a demanda por produtividade e manutenibilidade, mas respeitar restrições naturais deste tipo de sistema, tais como espaço de memória, potência e desempenho. As ferramentas de automação de projeto lidam com produtividade e manutenibilidade ao permitir especificações de alto nível, tarefa difícil de atender no domínio embarcado devido ao comportamento misto de muitas aplicações embarcadas. Abordagens que promovem meios para verificação formal também são atrativas, embora geralmente sejam difíceis de usar, e por este motivo não são de grande auxílio na tarefa de reduzir o tempo de chegada ao mercado do produto. Através do uso de Alloy, baseada em lógica de primeira-ordem, é possível obter especificações em altonível e verificação formal de modelos com uma única linguagem. Este trabalho apresenta a poderosa abstração proporcionada pela linguagem Alloy em aplicações embarcadas, assim como regras para obter automaticamente código Java a partir de modelos Alloy. A geração de código Java a partir de modelos Alloy, combinada a uma ferramenta de estimativa, provê exploração de espaço de projeto, atendendo assim as fortes restrições do projeto de software embarcado, o que normalmente não é contemplado pela engenharia de software tradicional. / This work proposes a new approach for embedded software development, by combining the abstraction and model verification properties of the Alloy declarative language with the broad acceptance in industry of Java. The approach comes into play since software automation in the embedded domain has become a major need, as currently most of the development time is spent designing software for such hardconstrained resources products. Design automation tools for embedded systems must meet the demand for productivity and maintainability, but constraints such as memory, power and performance must still be considered. Design automation tools deal with productivity and maintainability by allowing high-level specifications, which is hard to accomplish on the embedded domain due to the mixed behavior nature of many embedded applications. Approaches that provide means for formal verification are also attractive, but their usage is usually not straightforward, and for this reason they are not that helpful in dealing with time-tomarket constraints. By using Alloy, based in first-order logic, it is possible to obtain high-level specifications and formal model verification with a single language. This work shows the powerful abstraction provided by the Alloy language for embedded applications, as well as rules for obtaining automatically Java code from Alloy models. The Java source code generation from Alloy models, combined with an estimation tool, provides design space exploration to match tight embedded software design constraints, what is usually not taken into account by standard software engineering techniques.

<p>This thesis discusses the reasons for space exploration and space science. Space plasma physics is identified as an essential building block to understand the space environment and it is argued that observation and analysis of space plasma waves is an important approach.</p><p>Space plasma waves are the main actors in many important processes. So-called broadband waves are found responsible for much of the ion heating in the auroral region. We investigate the wave properties of broadband waves and show that they can be described as a mixture of electrostatic wave modes. In small regions void of cold electrons the broadband activity is found to be ion acoustic waves and these regions are also identified as acceleration regions. The identification of the wave modes includes reconstructions of the wave distribution function. The reconstruction technique allow us to determine the wave vector spectrum, which cannot be measured directly. The method is applied to other wave events and it is compared in some detail with a similar method.</p><p>Space plasma wave are also sensitive tools for investigations of both the fine-structure and the dynamics of space plasmas. Studies of whistler mode waves observed in the boundary layer on the magnetospheric side of the magnetopause reveal that the plasma is organized in tube-like structures moving with the plasma drift velocity. The perpendicular dimension of these tubes is of the order of the electron inertial length. We present evidence that each tube is linked to a reconnection site and argue that the high density of tube-like structures indicates patchy reconnection.</p>

This thesis discusses the reasons for space exploration and space science. Space plasma physics is identified as an essential building block to understand the space environment and it is argued that observation and analysis of space plasma waves is an important approach. Space plasma waves are the main actors in many important processes. So-called broadband waves are found responsible for much of the ion heating in the auroral region. We investigate the wave properties of broadband waves and show that they can be described as a mixture of electrostatic wave modes. In small regions void of cold electrons the broadband activity is found to be ion acoustic waves and these regions are also identified as acceleration regions. The identification of the wave modes includes reconstructions of the wave distribution function. The reconstruction technique allow us to determine the wave vector spectrum, which cannot be measured directly. The method is applied to other wave events and it is compared in some detail with a similar method. Space plasma wave are also sensitive tools for investigations of both the fine-structure and the dynamics of space plasmas. Studies of whistler mode waves observed in the boundary layer on the magnetospheric side of the magnetopause reveal that the plasma is organized in tube-like structures moving with the plasma drift velocity. The perpendicular dimension of these tubes is of the order of the electron inertial length. We present evidence that each tube is linked to a reconnection site and argue that the high density of tube-like structures indicates patchy reconnection.

Dans le cadre de la synthèse de haut niveau (SHN), qui permet d'extraire un modèle structural à partir d'un modèle algorithmique, nous proposons des solutions pour opti- miser l'accès et le transfert de données du matériel cible. Une méthodologie d'exploration de l'espace des architectures mémoire possibles a été mise au point. Cette méthodologie trouve un compromis entre la quantité de mémoire interne utilisée et les performances temporelles du matériel généré. Deux niveau d'optimisation existe : 1. Une optimisation architecturale, qui consiste à créer une hiérarchie mémoire, 2. Une optimisation algorithmique, qui consiste à partitionner la totalité des données manipulées pour stocker en interne seulement celles qui sont utiles dans l'immédiat. Pour chaque répartition possible, nous résolvons le problème de l'ordonnancement des calculs et de mapping des données. À la fin, nous choisissons la ou les solutions pareto. Nous proposons un outil, front-end de la SHN, qui est capable d'appliquer l'optimisation algorithmique du point 2 à un algorithme de traitement d'image spécifié par l'utilisateur. L'outil produit en sortie un modèle algorithmique optimisé pour la SHN, en customisant une architecture générique.

University of Macau / Faculty of Law

In the design of a multi-processor System-on-a-Chip (SoC), the bus architecture typically comes to the forefront because the system performance is not dependent only on the speed of the Processing Elements (PEs) but also on the bus architecture in the system. An efficient bus architecture with effective arbitration for reducing contention on the bus plays an important role in maximizing performance. Therefore, among many issues of multi-processor SoC research, we focus on two issues related to the bus architecture in this dissertation. One issue is how to quickly and easily design an efficient bus architecture for an SoC. The second issue is how to quickly explore the design space across performance influencing factors to achieve a high performance bus system. The objective of this research is to provide a Computer-Aided Design (CAD) tool with which the user can quickly explore System-on-a-Chip (SoC) bus design space in search of a high performance SoC bus system. From a straightforward description of the numbers and types of Processing Elements (PEs), non-PEs, memories and buses (including, for example, the address and data bus widths of the buses and memories), our Bus Synthesis tool, called BusSynth, generates a Register-Transfer Level (RTL) Verilog Hardware Description Language (HDL) description of the specified bus system. The user can utilize this RTL Verilog in bus-accurate simulations to more quickly arrive at an efficient bus architecture for a multi-processor SoC. The methodology we propose gives designers a great benefit in fast design space exploration of bus systems across a variety of performance influencing factors such as bus types, PE types and software programming styles (e.g., pipelined parallel fashion or functional parallel fashion). We also show that BusSynth can efficiently generate bus systems in a matter of seconds as opposed to weeks of design effort to integrate together each system component by hand. Moreover, unlike the previous related work, BusSynth can support a wide variety of PEs, memory types and bus architectures (including a hybrid bus architecture) in search of a high performance SoC.

Recent years have witnessed the emergence of microprocessors that are embedded within a plethora of devices used in everyday life. Embedded architectures are customized through a meticulous and time consuming design process to satisfy stringent constraints with respect to performance, area, power, and cost. In embedded systems, the cost of the memory hierarchy limits its ability to play as central a role. This is due to stringent constraints that fundamentally limit the physical size and complexity of the memory system. Ultimately, application developers and system engineers are charged with the heavy burden of reducing the memory requirements of an application. This thesis offers the intriguing possibility that compilers can play a significant role in the automatic design space exploration and optimization of embedded memory systems. This insight is founded upon a new analytical model and novel compiler optimizations that are specifically designed to increase the synergy between the processor and the memory system. The analytical models serve to characterize intrinsic program properties, quantify the impact of compiler optimizations on the memory systems, and provide deep insight into the trade-offs that affect memory system design.