694 research outputs found

    Vanishing value chains, industrial districts and HRM in the Brazilian automotive industry

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    Industrial districts in the Brazilian automotive industry have facilitated just-in-time production, functional flexibility, and compatibility of HR practices since the 1980s. However, this model has been threatened by global over-capacity and the rise of low cost suppliers in South Korea and China. This paper develops literature on proximity dynamics though exploring the influence of global supply chains on HRM in industrial districts. The more specific research questions are: How viable are industrial districts in the context of global crises? And how is this viability bound up with the awareness of HR practices down the supply chain? The findings indicate that the industrial districts model is under threat. In the context of global supply chains, automotive majors have shifted costs onto their suppliers, disrupting established relationships, and moreover, they often lack knowledge of the employment practices of distant suppliers. Yet, in times of political and economic uncertainty, worker rights might be best served by geographical and cognitive proximity

    Efficient Synthesis of Sensor Deception Attacks Using Observation Equivalence-Based Abstraction

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    This paper investigates the synthesis of successful sensor deception attack functions in supervisory control using abstraction methods to reduce computational complexity. In sensor deception attacks, an attacker hijacks a subset of the sensors of the plant and feeds incorrect information to the supervisor with the intent on causing damage to the supervised system. The attacker is successful if its attack causes damage to the system and it is not identified by an intrusion detection module. The existence test and the synthesis method of successful sensor deception attack functions are computationally expensive, specifically in partially observed systems. For this reason, we leverage results on abstraction methods to reduce the computational effort in solving these problems. Namely, we introduce an equivalence relation called restricted observation equivalence, that is used to abstract the original system before calculating attack functions. Based on this equivalence relation we prove that the existence of successful attack functions in the abstracted supervised system guarantees the existence of successful attack functions in the unabstracted supervised system and vice versa. Moreover, successful attack functions synthesized from the abstracted system can be exactly mapped to successful attack functions on the unabstracted system, thereby providing a complete solution to the attack synthesis problem

    Regras para classificação de ocorrências de ferrugem asiática da soja com base em variáveis meteorológicas.

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    Resumo. A ferrugem asiática é uma das doenças mais importantes e agressivas da soja, especialmente no Brasil. O uso de modelos matemáticos e computacionais podem auxiliar a tomada de decisão do produtor sobre a necessidade e o momento de uma ação de prevenção à doença. Modelos em árvore de decisão baseados em temperatura e precipitação foram desenvolvidos e extraídas regras que permitiram identificar os principais fatores que influenciaram a ocorrência da ferrugem em lavouras comerciais. O modelo final se mostrou interpretável e coerente com a literatura existente.SBIAgro 2013

    Mineração de dados para a análise e o alerta da ferrugem asiática da soja.

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    A proposta deste trabalho é utilizar técnicas de mineração de dados (data mining), também conhecida como processo de descoberta de conhecimento em bases de dados (Knowledge Discovery in Databases, KDD), para encontrar padrões em bases de dados relacionadas com a cultura da soja, ferrugem asiática e variáveis climáticas, de maneira semelhante à realizada por Meira (2008)

    Behaviour of cementitious matrices subjected to the combined action of chloride ions and carbonation

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    Carbonation and chloride action are the two leading causes of degradation in reinforced concrete structures. Despite the combined action of these two mechanisms being a reality, there is little research on the effect of this combination in cementitious matrices. Furthermore, the incorporation of fly ash in cementitious matrices has been frequently used in order to make the matrix more resistant to the action of chlorides. On the other hand, it is known that Ca(OH)2 existing in the matrix is consumed by the pozzolanic reactions, which makes easier the carbonation front advance. Therefore, this paper presents a study of the behavior of cementitious matrices, with and without fly ash, subjected to the combined action of chlorides and carbonation. Two different kinds of mortars were produced: reference (only cement CEM I 42.5R) and fly ash mortar (40% replacement of cement). After curing, the specimens were subjected to three different wetting-drying cycles, considering NaCl solutions and CO2 atmospheres. Afterwards, chloride profiles and carbonation front were measured. Results show that carbonation has a direct influence on chloride penetration, decreasing it for cement mortars with 0% fly ash and increasing it for mortars with 40% cement replacement by fly ash. Moreover, the evolution of carbonation is also influenced by chloride presence, which decreases under the combined action.The authors thank the Foundation for Science and Technology (FCT) for supporting this research. The authors also thank the SECIL for making available cement used in this research and the CIMENTEIRA DO LOURO for providing the aggregates used. This work is co-financed by FEDER funds through the Competitively Factors Operational Programme - COMPETE and by national funds through FCT within the scope of the project POCI-01-0145-FEDER007136.info:eu-repo/semantics/publishedVersio

    Mining structural signatures in proteins using intrachain interactions.

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    In this work we use a data mining approach to analyze similarity of proteins and to extract conserved information on dissimilar sequences of proteins of the same family.X-meeting 2007

    O efeito da adição de 40% de cinzas volantes sobre o ingresso de cloretos no betão face à ação combinada entre a carbonatação e os iões cloreto

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    Além de imprimir um caráter sustentável ao betão, as cinzas volantes (CV) têm sido bastante utilizadas para tornar a matriz cimentícia mais resistente à penetração de Cl-uma vez que tornam a estrutura porosa mais densa e ajudam a fixar Cl-. Por outro lado, sabe-se que o Ca(OH)2 existente na matriz é parcialmente consumido pelas reações pozolânicas, facilitando o avanço da carbonatação e, consequentemente, aumentando a quantidade de Cl-livres. Considerando a ação conjunta destes agentes, especula-se sobre o papel das CV na penetração de Cl-. Foram moldados provetes com 0% e 40% de CV. Após 90 dias de cura os provetes foram submetidos a 12 ciclos de imersão em solução com NaCl e secagem em câmara de carbonatação , num total de 168 dias. Observou-se que os provetes contendo CV, e submetidos à ação combinada, apresentaram perfis de Cl-com teores superiores quando comparados à ação exclusiva dos Cl

    Coherent states of non-relativistic electron in magnetic-solenoid field

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    We construct coherent states of a nonrelativistic electron in the magnetic-solenoid field, which is a superposition of the Aharonov-Bohm field and a collinear uniform magnetic field. In the problem under consideration there are two kind of coherent states, the first kind corresponds to classical trajectories which embrace the solenoid and the second one to trajectories which do not. Mean coordinates in the constructed coherent states are moving along classical trajectories, the coherent states maintain their form under the time evolution, and represent a complete set of functions, which can be useful in semi classical calculations. In the absence of the Aharonov-Bohm filed these states are reduced to the well-known in the case of uniform magnetic field Malkin-Man'ko coherent states.Comment: 11 pages, version accepted for publication in J. Phys. A, 3 figures adde
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