Aceleração da legalização incremental mediante o uso de árvores espaciais

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência da Computação, Florianópolis, 2017.Na síntese física de circuitos integrados, a etapa de legalização é responsável por remover sobreposições de células e alinhá-las com as linhas e colunas do circuito, enquanto minimiza o deslocamento das células. Esta etapa é aplicada não somente após o posicionamento global, mas também após etapas de otimização incremental tais como posicionamento incremental guiado por atraso, gate sizing e inserção de buffers. Quando utilizada em técnicas de otimização incremental, a legalização pode ser aplicada como um passo final, após cada iteração da otimização,ou de maneira incremental, após cada transformação no posicionamento. Infelizmente, técnicas recentes de legalização incremental utilizam estruturas de dados que não são adequadas para o armazenamento de informações sobre geometrias. Além disso, apesar de diferentes estratégias de legalização serem utilizadas por diferentes trabalhos de otimização incremental, estes trabalhos não apresentam resultados quantitativos do impacto destas estratégias no tempo de execução e qualidade da solução final. Este trabalho propõe uma técnica de legalização incremental utilizando uma estrutura de dados chamada R-tree, projetada para o armazenamento de informações sobre geometrias, permitindo buscas espaciais rápidas. A técnica proposta foi comparada atécnicas do estado da arte em legalização incremental, assim como às estratégias de legalização final e iterativa. Os resultados experimentais mostram que a técnica proposta é pelo menos 6 vezes mais rápida e realiza o mesmo número de legalizações quando comparado a outras técnicas de legalização incremental do estado da arte. Além disso, o algoritmo proposto é mais rápido que as estratégias de legalização final e iterativa, enquanto resulta em uma solução com perfil de densidade e comprimento das interconexões semelhante.Abstract : In the physical synthesis of digital circuits, circuit legalization removes overlaps and keeps cell alignment with circuit rows and sites while minimizing total cell displacement. Legalization is applied not only after global placement, but also after incremental optimization steps like incremental timing-driven placement, gate sizing, and buffer insertion. In the case of incremental optimization techniques, the legalization stepcan be applied as a final step, after each optimization iteration or incrementally, after each cell movement. Unfortunately, recent incremental legalization techniques employ data structures that are not suitable for handling geometry information. In addition, despite different legalization strategies are used by different works on incremental optimization, those works do not present quantitative results on how those strategies impact on the runtime and quality of the final solution. This work proposes a new legalization technique that relies on an R-tree, a data structure tailored to efficient geometry information storage, which allows for fast spatial search. The proposed technique was compared to state-of-the-art incremental legalization techniques, as well as to the final and iterative legalization strategies. Experimental results show that the proposed technique is at least 6 times faster and performs as many successful legalizations when compared to the related work on incremental legalization. In addition, it is faster than both the other two legalization strategies, while resulting in a solution with similar density profile and circuit wirelength

Timing optimization during the physical synthesis of cell-based VLSI circuits

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Automação e Sistemas, Florianópolis, 2016.Abstract : The evolution of CMOS technology made possible integrated circuits with billions of transistors assembled into a single silicon chip, giving rise to the jargon Very-Large-Scale Integration (VLSI). The required clock frequency affects the performance of a VLSI circuit and induces timing constraints that must be properly handled by synthesis tools. During the physical synthesis of VLSI circuits, several optimization techniques are used to iteratively reduce the number of timing violations until the target clock frequency is met. The dramatic increase of interconnect delay under technology scaling represents one of the major challenges for the timing closure of modern VLSI circuits. In this scenario, effective interconnect synthesis techniques play a major role. That is why this thesis targets two timing optimization problems for effective interconnect synthesis: Incremental Timing-Driven Placement (ITDP) and Incremental Timing-Driven Layer Assignment (ITLA). For solving the ITDP problem, this thesis proposes a new Lagrangian Relaxation formulation that minimizes timing violations for both setup and hold timing constraints. This work also proposes a netbased technique that uses Lagrange multipliers as net-weights, which are dynamically updated using an accurate timing analyzer. The netbased technique makes use of a novel discrete search to relocate cells by employing the Euclidean distance to define a proper neighborhood. For solving the ITLA problem, this thesis proposes a network flow approach that handles simultaneously critical and non-critical segments, and exploits a few flow conservation conditions to extract timing information for each net segment individually, thereby enabling the use of an external timing engine. The experimental validation using benchmark suites derived from industrial circuits demonstrates the effectiveness of the proposed techniques when compared with state-of-the-art works.A evolução da tecnologia CMOS viabilizou a fabricação de circuitos integrados contendo bilhões de transistores em uma única pastilha de silício, dando origem ao jargão Very-Large-Scale Integration (VLSI). A frequência-alvo de operação de um circuito VLSI afeta o seu desempenho e induz restrições de timing que devem ser manipuladas pelas ferramentas de síntese. Durante a síntese física de circuitos VLSI, diversas técnicas de otimização são usadas para iterativamente reduzir o número de violações de timing até que a frequência-alvo de operação seja atingida. O aumento dramático do atraso das interconexões devido à evolução tecnológica representa um dos maiores desafios para o fluxo de timing closure de circuitos VLSI contemporâneos. Nesse cenário, técnicas de síntese de interconexão eficientes têm um papel fundamental. Por este motivo, esta tese aborda dois problemas de otimização de timing para uma síntese eficiente das interconexões de um circuito VLSI: Incremental Timing-Driven Placement (ITDP) e Incremental Timing-Driven Layer Assignment (ITLA). Para resolver o problema de ITDP, esta tese propõe uma nova formulação utilizando Relaxação Lagrangeana que tem por objetivo a minimização simultânea das violações de timing para restrições do tipo setup e hold. Este trabalho também propõe uma técnica que utiliza multiplicadores de Lagrange como pesos para as interconexões, os quais são atualizados dinamicamente através dos resultados de uma ferramenta de análise de timing. Tal técnica realoca as células do circuito por meio de uma nova busca discreta que adota a distância Euclidiana como vizinhança.Para resolver o problema de ITLA, esta tese propõe uma abordagem em fluxo em redes que otimiza simultaneamente segmentos críticos e não-críticos, e explora algumas condições de fluxo para extrair as informações de timing para cada segmento individualmente, permitindo assim o uso de uma ferramenta de timing externa. A validação experimental, utilizando benchmarks derivados de circuitos industriais, demonstra a eficiência das técnicas propostas quando comparadas com trabalhos estado da arte

TopX : efficient and versatile top-k query processing for text, structured, and semistructured data

TopX is a top-k retrieval engine for text and XML data. Unlike Boolean engines, it stops query processing as soon as it can safely determine the k top-ranked result objects according to a monotonous score aggregation function with respect to a multidimensional query. The main contributions of the thesis unfold into four main points, confirmed by previous publications at international conferences or workshops: • Top-k query processing with probabilistic guarantees. • Index-access optimized top-k query processing. • Dynamic and self-tuning, incremental query expansion for top-k query processing. • Efficient support for ranked XML retrieval and full-text search. Our experiments demonstrate the viability and improved efficiency of our approach compared to existing related work for a broad variety of retrieval scenarios.TopX ist eine Top-k Suchmaschine für Text und XML Daten. Im Gegensatz zu Boole\u27; schen Suchmaschinen terminiert TopX die Anfragebearbeitung, sobald die k besten Ergebnisobjekte im Hinblick auf eine mehrdimensionale Anfrage gefunden wurden. Die Hauptbeiträge dieser Arbeit teilen sich in vier Schwerpunkte basierend auf vorherigen Veröffentlichungen bei internationalen Konferenzen oder Workshops: • Top-k Anfragebearbeitung mit probabilistischen Garantien. • Zugriffsoptimierte Top-k Anfragebearbeitung. • Dynamische und selbstoptimierende, inkrementelle Anfrageexpansion für Top-k Anfragebearbeitung. • Effiziente Unterstützung für XML-Anfragen und Volltextsuche. Unsere Experimente bestätigen die Vielseitigkeit und gesteigerte Effizienz unserer Verfahren gegenüber existierenden, führenden Ansätzen für eine weite Bandbreite von Anwendungen in der Informationssuche

Analyzing Granger causality in climate data with time series classification methods

Attribution studies in climate science aim for scientifically ascertaining the influence of climatic variations on natural or anthropogenic factors. Many of those studies adopt the concept of Granger causality to infer statistical cause-effect relationships, while utilizing traditional autoregressive models. In this article, we investigate the potential of state-of-the-art time series classification techniques to enhance causal inference in climate science. We conduct a comparative experimental study of different types of algorithms on a large test suite that comprises a unique collection of datasets from the area of climate-vegetation dynamics. The results indicate that specialized time series classification methods are able to improve existing inference procedures. Substantial differences are observed among the methods that were tested

The Proceedings of the 23rd Annual International Conference on Digital Government Research (DGO2022) Intelligent Technologies, Governments and Citizens June 15-17, 2022

The 23rd Annual International Conference on Digital Government Research theme is “Intelligent Technologies, Governments and Citizens”. Data and computational algorithms make systems smarter, but should result in smarter government and citizens. Intelligence and smartness affect all kinds of public values - such as fairness, inclusion, equity, transparency, privacy, security, trust, etc., and is not well-understood. These technologies provide immense opportunities and should be used in the light of public values. Society and technology co-evolve and we are looking for new ways to balance between them. Specifically, the conference aims to advance research and practice in this field. The keynotes, presentations, posters and workshops show that the conference theme is very well-chosen and more actual than ever. The challenges posed by new technology have underscored the need to grasp the potential. Digital government brings into focus the realization of public values to improve our society at all levels of government. The conference again shows the importance of the digital government society, which brings together scholars in this field. Dg.o 2022 is fully online and enables to connect to scholars and practitioners around the globe and facilitate global conversations and exchanges via the use of digital technologies. This conference is primarily a live conference for full engagement, keynotes, presentations of research papers, workshops, panels and posters and provides engaging exchange throughout the entire duration of the conference

U.S. Commission on Immigration Reform

The U.S. Commission on Immigration Reform was created by Congress to assess U.S. immigration policy and make recommendations regarding its implementation and effects. Mandated in the Immigration Act of 1990 to submit an interim report in 1994 and a final report in 1997, the Commission has undertaken public hearings, fact-finding missions, and expert consultations to identify the major immigration-related issues facing the United States today.LBJ School of Public Affair

Public Law and Economics

This comprehensive textbook applies economic analysis to public law. The economic analysis of law has revolutionized legal scholarship and teaching in the last half-century, but it has focused mostly on private law, business law, and criminal law. This book extends the analysis to fundamental topics in public law, such as the separation of government powers, regulation by agencies, constitutional rights, and elections. Every public law involves six fundamental processes of government: bargaining, voting, entrenching, delegating, adjudicating, and enforcing. The book devotes two chapters to each process, beginning with the economic theory and then applying the theory to a wide range of puzzles and problems in law. Each chapter concentrates on cases and legal doctrine, showing the relevance of economics to the work of lawyers and judges. Featuring lucid, accessible writing and engaging examples, the book addresses enduring topics in public law as well as modern controversies, including gerrymandering, voter identification laws, and qualified immunity for police

Public Law and Economics

This comprehensive textbook applies economic analysis to public law. The economic analysis of law has revolutionized legal scholarship and teaching in the last half-century, but it has focused mostly on private law, business law, and criminal law. This book extends the analysis to fundamental topics in public law, such as the separation of government powers, regulation by agencies, constitutional rights, and elections. Every public law involves six fundamental processes of government: bargaining, voting, entrenching, delegating, adjudicating, and enforcing. The book devotes two chapters to each process, beginning with the economic theory and then applying the theory to a wide range of puzzles and problems in law. Each chapter concentrates on cases and legal doctrine, showing the relevance of economics to the work of lawyers and judges. Featuring lucid, accessible writing and engaging examples, the book addresses enduring topics in public law as well as modern controversies, including gerrymandering, voter identification laws, and qualified immunity for police

An aesthetic for sustainable interactions in product-service systems?

Copyright @ 2012 Greenleaf PublishingEco-efficient Product-Service System (PSS) innovations represent a promising approach to sustainability. However the application of this concept is still very limited because its implementation and diffusion is hindered by several barriers (cultural, corporate and regulative ones). The paper investigates the barriers that affect the attractiveness and acceptation of eco-efficient PSS alternatives, and opens the debate on the aesthetic of eco-efficient PSS, and the way in which aesthetic could enhance some specific inner qualities of this kinds of innovations. Integrating insights from semiotics, the paper outlines some first research hypothesis on how the aesthetic elements of an eco-efficient PSS could facilitate user attraction, acceptation and satisfaction