Systematic delay-driven power optimisation and power-driven delay optimisation of combinational circuits

With the proliferation of mobile wireless communication and embedded systems, the energy efficiency becomes a major design constraint. The dissipated energy is often referred as the product of power dissipation and the input-output delay. Most of electronic design automation techniques focus on optimising only one of these parameters either power or delay. Industry standard design flows integrate systematic methods of optimising either area or timing while for power consumption optimisation one often employs heuristics which are characteristic to a specific design. In this work we answer three questions in our quest to provide a systematic approach to joint power and delay Optimisation. The first question of our research is: How to build a design flow which incorporates academic and industry standard design flows for power optimisation? To address this question, we use a reference design flow provided by Synopsys and integrate in this flow academic tools and methodologies. The proposed design flow is used as a platform for analysing some novel algorithms and methodologies for optimisation in the context of digital circuits. The second question we answer is: Is possible to apply a systematic approach for power optimisation in the context of combinational digital circuits? The starting point is a selection of a suitable data structure which can easily incorporate information about delay, power, area and which then allows optimisation algorithms to be applied. In particular we address the implications of a systematic power optimisation methodologies and the potential degradation of other (often conflicting) parameters such as area or the delay of implementation. Finally, the third question which this thesis attempts to answer is: Is there a systematic approach for multi-objective optimisation of delay and power? A delay-driven power and power-driven delay optimisation is proposed in order to have balanced delay and power values. This implies that each power optimisation step is not only constrained by the decrease in power but also the increase in delay. Similarly, each delay optimisation step is not only governed with the decrease in delay but also the increase in power. The goal is to obtain multi-objective optimisation of digital circuits where the two conflicting objectives are power and delay. The logic synthesis and optimisation methodology is based on AND-Inverter Graphs (AIGs) which represent the functionality of the circuit. The switching activities and arrival times of circuit nodes are annotated onto an AND-Inverter Graph under the zero and a non-zero-delay model. We introduce then several reordering rules which are applied on the AIG nodes to minimise switching power or longest path delay of the circuit at the pre-technology mapping level. The academic Electronic Design Automation (EDA) tool ABC is used for the manipulation of AND-Inverter Graphs. We have implemented various combinatorial optimisation algorithms often used in Electronic Design Automation such as Simulated Annealing and Uniform Cost Search Algorithm. Simulated Annealing (SMA) is a probabilistic meta heuristic for the global optimization problem of locating a good approximation to the global optimum of a given function in a large search space. We used SMA to probabilistically decide between moving from one optimised solution to another such that the dynamic power is optimised under given delay constraints and the delay is optimised under given power constraints. A good approximation to the global optimum solution of energy constraint is obtained. Uniform Cost Search (UCS) is a tree search algorithm used for traversing or searching a weighted tree, tree structure, or graph. We have used Uniform Cost Search Algorithm to search within the AIG network, a specific AIG node order for the reordering rules application. After the reordering rules application, the AIG network is mapped to an AIG netlist using specific library cells. Our approach combines network re-structuring, AIG nodes reordering, dynamic power and longest path delay estimation and optimisation and finally technology mapping to an AIG netlist. A set of MCNC Benchmark circuits and large combinational circuits up to 100,000 gates have been used to validate our methodology. Comparisons for power and delay optimisation are made with the best synthesis scripts used in ABC. Reduction of 23% in power and 15% in delay with minimal overhead is achieved, compared to the best known ABC results. Also, our approach is also implemented on a number of processors with combinational and sequential components and significant savings are achieved.

Medieval Irish vision literature: a genre study

This dissertation examines medieval literary accounts of visions of the afterlife with an origin or provenance in Ireland from the perspective of genre, analysing their structural and literary characteristics both synchronically and diachronically. To this end, I have developed a new typology of medieval vision literature. I address the question in what manner the internationally attested genre of vision literature is adapted and developed in an Irish literary milieu. I explore this central research question through an interrogation of the typological unity of the key texts, both in formal arrangement and in the eschatological themes they express. My analysis of the structure and rhetoric of these narratives reveals the primary role of identity strategies, question-and-answer patterns and exhortation for their narrative cohesion and didactic function. In addition, I was able to make a formal distinction at text-level between the adaptation of the genre as an autonomous unit and the adaptation of thematic motifs as topoi. This further enabled me to nuance the distribution of characteristic features in the genre. My analysis of the spatial and temporal aspects of the eschatological journey confirms a preoccupation with personal eschatology. It reveals a close connection between the development of the aspects of graded access and trial in the genre and a growing awareness of an interim state of the soul after death. Finally, my dissertation provides new editions, translations and analyses of primary sources. My research breaks new ground in the hitherto underexplored area of genre adaptation in Ireland. In addition, it contributes significantly to our understanding of the nature of vision literature both in an Irish and a European context, and to our knowledge of the transmission of eschatological thought in the Latin West. Discusses the visions of: Laisrén, Fursa, Adomnán, Lóchán, Tnugdal, Owein and Visio Sancti Pauli Redactions VI and XI.

Nietzsche and Montaigne: cheerful naturalism

The influence of the Essays of Michel de Montaigne on the thought of Friedrich Nietzsche has, hitherto, received scant scholarly attention. The aim of this thesis is to address this lacuna in the literature by making evident the importance of the Essays to the development of Nietzsche’s philosophy. I argue that, in order to fully appreciate Nietzsche’s thought, it must be recognized that, from the beginning to the end of his philosophical life, Montaigne was for him a thinker of the deepest personal and philosophical significance. Against the received scholarly opinion, which would see Montaigne as influential only for Nietzsche’s middle works, I contend that the Essays continue to be a key inspiration for Nietzsche even into his late and final works. Montaigne, with his cheerful affirmation of life, his experimental mode of philosophizing, and his resolutely naturalized perspective, was an exemplar for Nietzsche as a philosopher, psychologist, sceptic and naturalist. The Essays not only stimulated Nietzsche’s thinking on questions to do with morality, epistemology and the nature of the soul but also informed his conception of the ideal philosophical life. Moreover, to explore the Essays from a Nietzschean viewpoint, allows the drawing out of the more radical aspects of Montaigne’s thought, while to probe Montaigne’s impact on Nietzsche, provides insight into the trajectory of Nietzsche’s philosophy as he broke free from romantic pessimism and embraced the naturalism that would guide his works from Human, All Too Human onward.

Ontological representation of design science research publications

A search result provided by existing digital library and web search systems typically comprises only a prioritised list of possible publications or web pages that meet the search criteria, possibly with excerpts and possibly with search terms highlighted. The research in progress reported in this poster contributes to a larger research effort to provide a readable summary of search results that synthesise relevant publications or web pages to provide results that meet four C’s: comprehensive, concise, coherent, and correct, as a more useful alternative to un-synthesised result lists. The scope of this research is limited to searching for and synthesising Design Science Research (DSR) publications that present the results of DSR, as an example problem domain.