801 research outputs found

    Functions of rational Krylov space matrices and their decay properties

    Get PDF
    Rational Krylov subspaces have become a fundamental ingredient in numerical linear algebra methods associated with reduction strategies. Nonetheless, many structural properties of the reduced matrices in these subspaces are not fully understood. We advance in this analysis by deriving bounds on the entries of rational Krylov reduced matrices and of their functions, that ensure an a-priori decay of their entries as we move away from the main diagonal. As opposed to other decay pattern results in the literature, these properties hold in spite of the lack of any banded structure in the considered matrices. Numerical experiments illustrate the quality of our results

    Inexact Arnoldi residual estimates and decay properties for functions of non-Hermitian matrices

    Get PDF
    This paper derives a priori residual-type bounds for the Arnoldi approximation of a matrix function together with a strategy for setting the iteration accuracies in the inexact Arnoldi approximation of matrix functions. Such results are based on the decay behavior of the entries of functions of banded matrices. Specifically, a priori decay bounds for the entries of functions of banded non-Hermitian matrices will be exploited, using Faber polynomial approximation. Numerical experiments illustrate the quality of the results

    Severidade da Sigatoka-Amarela da bananeira, em função da nutrição mineral em solução nutritiva.

    Get PDF
    A sigatoka-amarela, cujo agente etiológico é o fungo Mycosphaerella musicola Leach (Stat. Conid. Cercospora musae Zimm.), é uma das mais importantes doenças da ananicultura, pois sua ocorrência está generalizada por diversas regiões produtoras, ocasionando prejuízos advindos da morte precoce das folhas e a consequente redução no crescimento e no desenvolvimento da planta, com reflexos evidentes na produção

    The Short-term Rational Lanczos Method and Applications

    Get PDF

    Investigation of the Reaction Mechanism between Bovine Collagen and a Triazine- Based Coupling Reagent

    Get PDF
    Content: The triazine-based coupling reagent 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) is a promptly water-soluble white solid commonly used in chemical synthesis, which is proven to act as effective tanning agent. This research work provides an experimental evidence that the tanning ability of DMTMM is associated to an increase of the cross-linking density in the collagen molecule. As a result of the coupling reaction, DMTMM is converted into water-soluble by-products that can be removed by washing. Take-Away: chrome free tanning, reaction mechanis

    A greenhouse gas inventory in the municipal landfill of the city of Limeira, Brazil

    Get PDF
    Landfill main gases are methane and carbon dioxide, and result mainly from the anaerobic digestion of organic waste. The exact distribution of gases in the landfill varies with the landfill age among other factors such as waste composition, moisture, particle size, temperature, pH, age of waste, landfill design and operation. The current Brazilian environmental legislation has encouraged the municipalities to adopt measures to reduce greenhouse gas (GHG) emissions from landfills. The implementation of projects to reduce GHG requires the estimation of the gases produced in the landfill. This research presents a GHG inventory performed in the landfill of the city of Limeira, located in the State of Sao Paulo, Brazil. The inventory was conducted by using the Brazilian GHG Protocol that follows the methodology of the Intergovernmental Panel on Climate Change (IPCC), and also IPCC guidelines. The inventory comprised data from 1985 to 2013; however, data prior to 2000 were estimated, because until that year the landfill was in fact a dump, with no monitoring of the amounts of wastes disposed of. Three categories of emissions were considered: a) direct emissions of CO2 and CH4 from the decomposition of municipal solid waste (MSW) and non-hazardous industrial waste and the emissions produced from waste transportation within the landfill and landfill operation; b) emissions resulting from electricity consumption within the operating limits of the landfill; and, c) indirect emissions from waste transportation throughout the city to the landfill and also from industries to the landfill. The results showed that in the year 2013 were emitted 35,996.91 t of CO2 e into the atmosphere. From the total, 98.91 % of emissions were produced by MSW decomposition; 0.002 % by industrial waste decomposition; 0.332 % by burning fossil fuels during landfill operation; 0.003 % by electricity consumption of electricity in the landfill and 0.75 % by waste transportation.Landfill main gases are methane and carbon dioxide, and result mainly from the anaerobic digestion of organic waste. The exact distribution of gases in the landfill varies with the landfill age among other factors such as waste composition, moisture, part4320832088sem informaçãosem informaçã
    corecore