HERQULES:System level cross-layer design exploration for efficient energy-quality trade-offs

In this paper, we present a unique cross-layer design framework that allows systematic exploration of the energy-delay-quality trade-offs at the algorithm, architecture and circuit level of design abstraction for each block of a system. In addition, taking into consideration the interactions between different sub-blocks of a system, it identifies the design solutions that can ensure the least energy at the "right amount of quality" for each sub-block/system under user quality/delay constraints. This is achieved by deriving sensitivity based design criteria, the balancing of which form the quantitative relations that can be used early in the system design process to evaluate the energy efficiency of various design options. The proposed framework when applied to the exploration of energy-quality design space of the main blocks of a digital camera and a wireless receiver, achieves 58% and 33% energy savings under 41% and 20% error increase, respectively. © 2010 ACM.

Containing the Nanometer "Pandora-Box": Cross-Layer Design Techniques for Variation Aware Low Power Systems

The demand for richer multimedia services, multifunctional portable devices and high data rates can only been visioned due to the improvement in semiconductor technology. Unfortunately, sub-90 nm process nodes uncover the nanometer Pandora-box exposing the barriers of technology scaling-parameter variations, that threaten the correct operation of circuits, and increased energy consumption, that limits the operational lifetime of today's systems. The contradictory design requirements for low-power and system robustness, is one of the most challenging design problems of today. The design efforts are further complicated due to the heterogeneous types of designs ( logic, memory, mixed-signal) that are included in today's complex systems and are characterized by different design requirements. This paper presents an overview of techniques at various levels of design abstraction that lead to low power and variation aware logic, memory and mixed-signal circuits and can potentially assist in meeting the strict power budgets and yield/quality requirements of future systems.

Distributed Region-Based Memory Allocation and Synchronization

We present DRASync, a region-based allocator that implements a global address space abstraction for MPI programs with pointer-based data structures. The main features of DRASync are: (a) it amortizes communication among nodes to allow efficient parallel allocation in a global address space; (b) it takes advantage of bulk deallocation and good locality with pointer-based data structures; (c) it supports ownership semantics of regions by nodes akin to reader–writer locks, which makes for a high-level, intuitive synchronization tool in MPI programs, without sacrificing message-passing performance. We evaluate DRASync against a state-of-the-art distributed allocator and find that it produces comparable performance while offering a higher-level abstraction to programmers.

Dublin’s ephemeral and imaginary architectures

In 1989, the Irish architectural practice O’Donnell and Tuomey were commissioned to build a temporary pavilion to represent Ireland at the 11 Cities/11 Nations exhibition at Leeuwarden in the Netherlands. Citing Peter Smithson, John Tuomey suggested the pavilion, which drew inspirations from the forms and materials of the modern Irish barn, embodied an intention ‘not just to build but to communicate’. Its subsequent reassembly for the inauguration of the Irish Museum of Modern Art in the courtyard of the seventeenth-century Royal Hospital Kilmainham in Dublin in 1991, drew comparisons between the urban sophistication of this colonial building, its svelte new refit, and the rural expression of O’Donnell + Tuomey’s barn. It was, one critic recently noted, as if ‘a wedding had been crashed by a country cousin who had forgotten to clean his boots’.
It has been argued that temporary or ephemeral pieces of architecture, unburdened by the traditional constraints of firmitas or utilitas, have the ability to offer a concise distillation of meaning and intention. Approaching the qualities of rhetoric, such architectures share similarities with the monument and yet differ in fundamental ways. Their rapid construction in lightweight materials can allow for an almost instantaneous negotiation of zeitgeist. And, unlike the monument, from the outset the space and form of these installations is designed to disappear.
This paper analyses the ephemeral architectures of Dublin in the modern period contextualising their qualities and intentions as they manifest themselves across colonial, post-colonial and contemporary epochs. It finds origins in the theatrical sets of the late eighteenth century and traces their movements into the semi-public sphere of the pleasure garden and finally into the theatre of the streets. It is here that temporary architecture in the city has been at its most potent, allowing the amplification or subversion of the meanings of much larger spaces. Historically, much of Dublin’s most conspicuous instances of ephemeral architecture have been realised as a means of articulating mass spectacle in political, religious or nationalistic events. And while much of this has sought to confirm dominant ideologies, it has also been possible to discern moments of opposition.
The contemporary period, however, has arguably witnessed a shift in ephemeral architectures from explicitly representing ‘positive ideologies’ towards something more oblique or nebulous. This turn towards abstraction in form and space has rendered an especially communicative form of architecture particularly elusive. By examining continuities within the apparent disjuncture between historical and contemporary examples, this paper begins to unpick the language of recent ephemeral architecture in Dublin and situate it within wider global trends where political and economic imperatives are often simultaneously obscured and expressed in public space by a vocabulary of universality. As Jurgen Habermas has suggested, the contemporary value given to the transitory and the ephemeral ‘discloses a longing for an undefiled, immaculate and stable present’.

Chemistry and Distribution of Daughter Species in the Circumstellar Envelopes of O-Rich AGB Stars

Context. Thanks to the advent of Herschel and ALMA, new high-quality observations of molecules present in the circumstellar envelopes of asymptotic giant branch (AGB) stars are being reported that reveal large differences from the existing chemical models. New molecular data and more comprehensive models of the chemistry in circumstellar envelopes are now available.
Aims: The aims are to determine and study the important formation and destruction pathways in the envelopes of O-rich AGB stars and to provide more reliable predictions of abundances, column densities, and radial distributions for potentially detectable species with physical conditions applicable to the envelope surrounding IK Tau.
Methods: We use a large gas-phase chemical model of an AGB envelope including the effects of CO and N2 self-shielding in a spherical geometry and a newly compiled list of inner-circumstellar envelope parent species derived from detailed modeling and observations. We trace the dominant chemistry in the expanding envelope and investigate the chemistry as a probe for the physics of the AGB phase by studying variations of abundances with mass-loss rates and expansion velocities.
Results: We find a pattern of daughter molecules forming from the photodissociation products of parent species with contributions from ion-neutral abstraction and dissociative recombination. The chemistry in the outer zones differs from that in traditional PDRs in that photoionization of daughter species plays a significant role. With the proper treatment of self-shielding, the N → N2 and C+→ CO transitions are shifted outward by factors of 7 and 2, respectively, compared with earlier models. An upper limit on the abundance of CH4 as a parent species of (≲2.5 × 10-6 with respect to H2) is found for IK Tau, and several potentially observable molecules with relatively simple chemical links to other parent species are determined. The assumed stellar mass-loss rate, in particular, has an impact on the calculated abundances of cations and the peak-abundance radius of both cations and neutrals: as the mass-loss rate increases, the peak abundance of cations generally decreases and the peak-abundance radius of all species moves outwards. The effects of varying the envelope expansion velocity and cosmic-ray ionization rate are not as significant.

‘Twenty-six things at once’: Pragmatic perspectives on Frank O’Hara and Norman Bluhm’s Poem-Paintings

Created over a couple of Sunday mornings in the Fall of 1960, the twenty-six collaborative Poem-Paintings of the artist Norman Bluhm and the poet Frank O'Hara represent what Bluhm later called a spontaneous 'conversation' between the painter and the poet. In this essay, Catherine Gander adopts a number of pragmatist positions to reconsider these overlooked works as essential examples of verbal-visual interaction that extend their 'conversation' to greet and involve us in a relationship that is at once interpersonal, integrated, and embodied. The works, Gander argues, constitute what John Dewey terms 'art as experience'; in their back and forth exchange of verbal and visual gesture, abstraction and denotation, the Poem-Paintings are the 'cumulative continuity' of 'the process of living', dramatising the shifting, spontaneous and multiple dimensions of interpersonal conversation, and in so doing, indicating a new path toward interconnective and equal exchange between word and image.

Synthesis of FPGA-based accelerators implementing recursive algorithms

O desenvolvimento de sistemas computacionais é um processo complexo, com múltiplas etapas, que requer uma análise profunda do problema, levando em consideração as limitações e os requisitos aplicáveis. Tal tarefa envolve a exploração de técnicas alternativas e de algoritmos computacionais para optimizar o sistema e satisfazer os requisitos estabelecidos. Neste contexto, uma das mais importantes etapas é a análise e implementação de algoritmos computacionais. Enormes avanços tecnológicos no âmbito das FPGAs (Field-Programmable Gate Arrays) tornaram possível o desenvolvimento de sistemas de engenharia extremamente complexos. Contudo, o número de transístores disponíveis por chip está a crescer mais rapidamente do que a capacidade que temos para desenvolver sistemas que tirem proveito desse crescimento. Esta limitação já bem conhecida, antes de se revelar com FPGAs, já se verificava com ASICs (Application-Specific Integrated Circuits) e tem vindo a aumentar continuamente. O desenvolvimento de sistemas com base em FPGAs de alta capacidade envolve uma grande variedade de ferramentas, incluindo métodos para a implementação eficiente de algoritmos computacionais. Esta tese pretende proporcionar uma contribuição nesta área, tirando partido da reutilização, do aumento do nível de abstracção e de especificações algorítmicas mais automatizadas e claras. Mais especificamente, é apresentado um estudo que foi levado a cabo no sentido de obter critérios relativos à implementação em hardware de algoritmos recursivos versus iterativos. Depois de serem apresentadas algumas das estratégias para implementar recursividade em hardware mais significativas, descreve-se, em pormenor, um conjunto de algoritmos para resolver problemas de pesquisa combinatória (considerados enquanto exemplos de aplicação). Versões recursivas e iterativas destes algoritmos foram implementados e testados em FPGA. Com base nos resultados obtidos, é feita uma cuidada análise comparativa. Novas ferramentas e técnicas de investigação que foram desenvolvidas no âmbito desta tese são também discutidas e demonstradas.

Medical information extraction in European Portuguese

The electronic storage of medical patient data is becoming a daily experience in most of the practices and hospitals worldwide. However, much of the data available is in free-form text, a convenient way of expressing concepts and events, but especially challenging if one wants to perform automatic searches, summarization or statistical analysis. Information Extraction can relieve some of these problems by offering a semantically informed interpretation and abstraction of the texts. MedInX, the Medical Information eXtraction system presented in this document, is the first information extraction system developed to process textual clinical discharge records written in Portuguese. The main goal of the system is to improve access to the information locked up in unstructured text, and, consequently, the efficiency of the health care process, by allowing faster and reliable access to quality information on health, for both patient and health professionals. MedInX components are based on Natural Language Processing principles, and provide several mechanisms to read, process and utilize external resources, such as terminologies and ontologies, in the process of automatic mapping of free text reports onto a structured representation. However, the flexible and scalable architecture of the system, also allowed its application to the task of Named Entity Recognition on a shared evaluation contest focused on Portuguese general domain free-form texts. The evaluation of the system on a set of authentic hospital discharge letters indicates that the system performs with 95% F-measure, on the task of entity recognition, and 95% precision on the task of relation extraction. Example applications, demonstrating the use of MedInX capabilities in real applications in the hospital setting, are also presented in this document. These applications were designed to answer common clinical problems related with the automatic coding of diagnoses and other health-related conditions described in the documents, according to the international classification systems ICD-9-CM and ICF. The automatic review of the content and completeness of the documents is an example of another developed application, denominated MedInX Clinical Audit system.

Synchronisation in high-performance integrated circuits

A distribui ção de um sinal relógio, com elevada precisão espacial (baixo skew) e temporal (baixo jitter ), em sistemas sí ncronos de alta velocidade tem-se revelado uma tarefa cada vez mais demorada e complexa devido ao escalonamento da tecnologia. Com a diminuição das dimensões dos dispositivos e a integração crescente de mais funcionalidades nos Circuitos Integrados (CIs), a precisão associada as transições do sinal de relógio tem sido cada vez mais afectada por varia ções de processo, tensão e temperatura. Esta tese aborda o problema da incerteza de rel ogio em CIs de alta velocidade, com o objetivo de determinar os limites do paradigma de desenho sí ncrono. Na prossecu ção deste objectivo principal, esta tese propõe quatro novos modelos de incerteza com âmbitos de aplicação diferentes. O primeiro modelo permite estimar a incerteza introduzida por um inversor est atico CMOS, com base em parâmetros simples e su cientemente gen éricos para que possa ser usado na previsão das limitações temporais de circuitos mais complexos, mesmo na fase inicial do projeto. O segundo modelo, permite estimar a incerteza em repetidores com liga ções RC e assim otimizar o dimensionamento da rede de distribui ção de relógio, com baixo esfor ço computacional. O terceiro modelo permite estimar a acumula ção de incerteza em cascatas de repetidores. Uma vez que este modelo tem em considera ção a correla ção entre fontes de ruí do, e especialmente util para promover t ecnicas de distribui ção de rel ogio e de alimentação que possam minimizar a acumulação de incerteza. O quarto modelo permite estimar a incerteza temporal em sistemas com m ultiplos dom ínios de sincronismo. Este modelo pode ser facilmente incorporado numa ferramenta autom atica para determinar a melhor topologia para uma determinada aplicação ou para avaliar a tolerância do sistema ao ru ído de alimentação. Finalmente, usando os modelos propostos, são discutidas as tendências da precisão de rel ogio. Conclui-se que os limites da precisão do rel ogio são, em ultima an alise, impostos por fontes de varia ção dinâmica que se preveem crescentes na actual l ogica de escalonamento dos dispositivos. Assim sendo, esta tese defende a procura de solu ções em outros ní veis de abstração, que não apenas o ní vel f sico, que possam contribuir para o aumento de desempenho dos CIs e que tenham um menor impacto nos pressupostos do paradigma de desenho sí ncrono.

Seamless integration of heterogeneous networks in multicast environments

Nowadays, communication environments are already characterized by a myriad of competing and complementary technologies that aim to provide an ubiquitous connectivity service. Next Generation Networks need to hide this heterogeneity by providing a new abstraction level, while simultaneously be aware of the underlying technologies to deliver richer service experiences to the end-user. Moreover, the increasing interest for group-based multimedia services followed by their ever growing resource demands and network dynamics, has been boosting the research towards more scalable and exible network control approaches. The work developed in this Thesis enables such abstraction and exploits the prevailing heterogeneity in favor of a context-aware network management and adaptation. In this scope, we introduce a novel hierarchical control framework with self-management capabilities that enables the concept of Abstract Multiparty Trees (AMTs) to ease the control of multiparty content distribution throughout heterogeneous networks. A thorough evaluation of the proposed multiparty transport control framework was performed in the scope of this Thesis, assessing its bene ts in terms of network selection, delivery tree recon guration and resource savings. Moreover, we developed an analytical study to highlight the scalability of the AMT concept as well as its exibility in large scale networks and group sizes. To prove the feasibility and easy deployment characteristic of the proposed control framework, we implemented a proof-of-concept demonstrator that comprehends the main control procedures conceptually introduced. Its outcomes highlight a good performance of the multiparty content distribution tree control, including its local and global recon guration. In order to endow the AMT concept with the ability to guarantee the best service experience by the end-user, we integrate in the control framework two additional QoE enhancement approaches. The rst employs the concept of Network Coding to improve the robustness of the multiparty content delivery, aiming at mitigating the impact of possible packet losses in the end-user service perception. The second approach relies on a machine learning scheme to autonomously determine at each node the expected QoE towards a certain destination. This knowledge is then used by di erent QoE-aware network management schemes that, jointly, maximize the overall users' QoE. The performance and scalability of the control procedures developed, aided by the context and QoE-aware mechanisms, show the advantages of the AMT concept and the proposed hierarchical control strategy for the multiparty content distribution with enhanced service experience. Moreover we also prove the feasibility of the solution in a practical environment, and provide future research directions that bene t the evolved control framework and make it commercially feasible.

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How is it possible that civilization has a global understanding of the abstraction of the human form? At a subconscious level as humans we have the ability to find the form of the body in the most minimal of shapes, objects, landscape and even natural phenomena such as clouds, it is an ability inherent in human nature. This deep-rooted facility to recognise the human form at various levels of abstraction is also developed further by our life experiences, environment and total education; specifically in the fine and applied arts. For this research I have focused on the change between realistic representations of the human form to complete abstraction. I have broken it down to its most basic elements to explore at what point our visual language allows us to recognise and define a shape or object as being influenced by, or connected to, the human form. I have concentrated on extending my own visual language relating to the human form within my own practice. A series of practical research projects has been undertaken and has been supported by a new series of investigative works, drawings and written evidence of the ways in which the figure can be represented, documenting the process via the thesis and final works. As part of my research, I have investigated the way artists working with clay have abstracted the human form focusing in particular on work from the 1950s to the present day using clay, drawing and installation. I have looked at how, over this period, artists have developed their own visual signifiers of the human form within their abstract/representational creations. The aim of this research will be falls into two parts: • To investigate how far one can push the human form in clay before it moves into abstraction • To locate the vanishing point where viewers still identify the human within ceramic abstract sculpture

Olhares para a matemática depois de um processo de RVCC

Trabalho de projecto de mestrado, Ciências da Educação (Formação de Adultos), Universidade de Lisboa, Instituto de Educação, 2011

Joaquim Rodrigo:a contínua reinvenção da pintura

Tese de doutoramento, História (História da Arte), Universidade de Lisboa, Faculdade de Letras, 2014

Europa : paisagem e pensamento : um excurso sobre Teixeira de Pascoaes, Friedrich Hölderlin, José Marinho e Martin Heidegger

Tese de doutoramento, Filosofia (Filosofia em Portugal), Universidade de Lisboa, Faculdade de Letras, 2014

Labirintos da justiça na escola : representações e práticas de alunos e professores

Tese de doutoramento, Educação (Supervisão e Orientação da Prática Profissional), Universidade de Lisboa, Instituto de Educação, 2015