11,012 research outputs found

    Yielding of rockfill in relative humidity-controlled triaxial experiments

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    The final publication is available at Springer via http://dx.doi.org/10.1007/s11440-016-0437-9The paper reports the results of suction controlled triaxial tests performed on compacted samples of two well graded granular materials in the range of coarse sand-medium gravel particle sizes: a quartzitic slate and a hard limestone. The evolution of grain size distributions is discussed. Dilatancy rules were investigated. Dilatancy could be described in terms of stress ratio, plastic work input and average confining stress. The shape of the yield locus in a triaxial plane was established by different experimental techniques. Yielding loci in both types of lithology is well represented by approximate elliptic shapes whose major axis follows approximately the Ko line. Relative humidity was found to affect in a significant way the evolution of grain size distribution, the deviatoric stress-strain response and the dilatancy rules.Peer ReviewedPostprint (author's final draft

    Sistemas granulares evolutivos

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    Orientador: Fernando Antonio Campos GomideTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia ElĂ©trica e de ComputaçãoResumo: Recentemente tem-se observado um crescente interesse em abordagens de modelagem computacional para lidar com fluxos de dados do mundo real. MĂ©todos e algoritmos tĂȘm sido propostos para obtenção de conhecimento a partir de conjuntos de dados muito grandes e, a princĂ­pio, sem valor aparente. Este trabalho apresenta uma plataforma computacional para modelagem granular evolutiva de fluxos de dados incertos. Sistemas granulares evolutivos abrangem uma variedade de abordagens para modelagem on-line inspiradas na forma com que os humanos lidam com a complexidade. Esses sistemas exploram o fluxo de informação em ambiente dinĂąmico e extrai disso modelos que podem ser linguisticamente entendidos. Particularmente, a granulação da informação Ă© uma tĂ©cnica natural para dispensar atenção a detalhes desnecessĂĄrios e enfatizar transparĂȘncia, interpretabilidade e escalabilidade de sistemas de informação. Dados incertos (granulares) surgem a partir de percepçÔes ou descriçÔes imprecisas do valor de uma variĂĄvel. De maneira geral, vĂĄrios fatores podem afetar a escolha da representação dos dados tal que o objeto representativo reflita o significado do conceito que ele estĂĄ sendo usado para representar. Neste trabalho sĂŁo considerados dados numĂ©ricos, intervalares e fuzzy; e modelos intervalares, fuzzy e neuro-fuzzy. A aprendizagem de sistemas granulares Ă© baseada em algoritmos incrementais que constroem a estrutura do modelo sem conhecimento anterior sobre o processo e adapta os parĂąmetros do modelo sempre que necessĂĄrio. Este paradigma de aprendizagem Ă© particularmente importante uma vez que ele evita a reconstrução e o retreinamento do modelo quando o ambiente muda. Exemplos de aplicação em classificação, aproximação de função, predição de sĂ©ries temporais e controle usando dados sintĂ©ticos e reais ilustram a utilidade das abordagens de modelagem granular propostas. O comportamento de fluxos de dados nĂŁo-estacionĂĄrios com mudanças graduais e abruptas de regime Ă© tambĂ©m analisado dentro do paradigma de computação granular evolutiva. Realçamos o papel da computação intervalar, fuzzy e neuro-fuzzy em processar dados incertos e prover soluçÔes aproximadas de alta qualidade e sumĂĄrio de regras de conjuntos de dados de entrada e saĂ­da. As abordagens e o paradigma introduzidos constituem uma extensĂŁo natural de sistemas inteligentes evolutivos para processamento de dados numĂ©ricos a sistemas granulares evolutivos para processamento de dados granularesAbstract: In recent years there has been increasing interest in computational modeling approaches to deal with real-world data streams. Methods and algorithms have been proposed to uncover meaningful knowledge from very large (often unbounded) data sets in principle with no apparent value. This thesis introduces a framework for evolving granular modeling of uncertain data streams. Evolving granular systems comprise an array of online modeling approaches inspired by the way in which humans deal with complexity. These systems explore the information flow in dynamic environments and derive from it models that can be linguistically understood. Particularly, information granulation is a natural technique to dispense unnecessary details and emphasize transparency, interpretability and scalability of information systems. Uncertain (granular) data arise from imprecise perception or description of the value of a variable. Broadly stated, various factors can affect one's choice of data representation such that the representing object conveys the meaning of the concept it is being used to represent. Of particular concern to this work are numerical, interval, and fuzzy types of granular data; and interval, fuzzy, and neurofuzzy modeling frameworks. Learning in evolving granular systems is based on incremental algorithms that build model structure from scratch on a per-sample basis and adapt model parameters whenever necessary. This learning paradigm is meaningful once it avoids redesigning and retraining models all along if the system changes. Application examples in classification, function approximation, time-series prediction and control using real and synthetic data illustrate the usefulness of the granular approaches and framework proposed. The behavior of nonstationary data streams with gradual and abrupt regime shifts is also analyzed in the realm of evolving granular computing. We shed light upon the role of interval, fuzzy, and neurofuzzy computing in processing uncertain data and providing high-quality approximate solutions and rule summary of input-output data sets. The approaches and framework introduced constitute a natural extension of evolving intelligent systems over numeric data streams to evolving granular systems over granular data streamsDoutoradoAutomaçãoDoutor em Engenharia ElĂ©tric

    Industrial policy for the medium to long-term

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    This report reviews the market failure and systems failure rationales for industrial policy and assesses the evidence on part experience of industrial policy in the UK. In the light of this, it reviews options for reshaping the design and delivery of industrial policy towards UK manufacturing. These options are intended to encourage a medium- to long-term perspective across government departments and to integrate science, innovation and industrial policy

    Corporate strategy in turbulent environments: Key roles of the corporate level

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    This paper analyzes the evolution during the period 1986-2002 of the corporate strategy of Lujan, a highly successful car components manufacturer headquartered in Spain, as a way to explore how the corporate level influences the successful evolution of a company exposed to a "turbulent" environment over a long period. We find that the corporate level plays three key roles. First, it drives a firm's evolution by developing a cognitive representation of the firm's competitive landscape. Second, it paces the company's evolution by alternately shifting the balance of organizational initiatives between static efficiency-based "local search" strategies, chosen in times of stability or economic slowdown, and dynamic efficiency-based "long jump" strategies, adopted during periods of major environmental turbulence. Long-jump corporate strategies, carried out through limited downside strategic initiatives such as real options and strategic alliances ("off-line long-jumps"), are particularly frequent in these circumstances. The third role consists of developing an organizational architecture that frames the self-organized coordination of the different business divisions. The Lujan story clearly illustrates the important role of corporate strategy in a firm that must undergo radical transitions as a result of major environmental changes.corporate strategy; turbulent environments; complexity theory; car components;

    Granular technologies to accelerate decarbonization

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    Of the 45 energy technologies deemed critical by the International Energy Agency for meeting global climate targets, 38 need to improve substan- tially in cost and performance while accelerating deployment over the next decades.Low-carbon technological solutions vary in scale from solar panels, e-bikes, and smart thermostats to carbon capture and storage, light rail transit, and whole-building retrofits. We make three contributions to long-standing debates on the appropriate scale of technological responses in the energy system. First, we focus on the specific needs of accelerated low-carbon transformation: rapid technology deployment, escaping lock-in, and social legitimacy. Second, we synthesize evidence on energy end-use technologies in homes, transport, and industry, as well as electricity generation and energy supply. Third, we go beyond technical and economic considerations to include innovation, investment, deployment, social, and equity criteria for assessing the relative advantage of alternative technologies as a function of their scale. We suggest numerous potential advantages of more-granular energy technologies for accelerating progress toward climate targets, as well as the conditions on which such progress depends
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