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31.
This work presents an optimization model to support decisions in the aggregate production planning of sugar and ethanol milling
companies. The mixed integer programming formulation proposed is based on industrial process selection and production lot-sizing
models. The aim is to help the decision makers in selecting the industrial processes used to produce sugar, ethanol and molasses,
as well as in determining the quantities of sugarcane crushed, the selection of sugarcane suppliers and sugarcane transport
suppliers, and the final product inventory strategy. The planning horizon is the whole sugarcane harvesting season and decisions
are taken on a discrete fraction of time. A case study was developed in a Brazilian mill and the results highlight the applicability
of the proposed approach. 相似文献
32.
The 3 steps sequential extraction procedure proposed by the Standards Measurements and Testing program (SM&T--formerly BCR) of the European Union has been applied for the speciation of metals in sediments. Results obtained by the application of the BCR standardized procedure were compared to those of two four step sequential extraction procedures, which are different from the BCR procedure only for the introduction of an additional step with NaOCl, as 2nd and 3rd step respectively. Five different metals have been taken into consideration: Cd, Cu, Ni, Pb and Zn. The analytical performances of the laboratory have been evaluated using three certified reference materials: the BCR 601 lake sediment for the BCR sequential extraction procedure, PACS-1 and MESS-1 for total metal concentration. Results showed that the efficiency of NaOCl treatment is higher or at least equal to that of H2O2 treatment and that its selectivity is quite satisfying. Moreover the NaOCl treatment doesn't significantly influence the extraction of the easily reducible fraction. 相似文献
33.
Asymptotic stability analysis in uncertain multi-delayed state neural networks via Lyapunov–Krasovskii theory 总被引:1,自引:0,他引:1
Fernando O. Souza Reinaldo M. Palhares Petr Ya. Ekel 《Mathematical and Computer Modelling》2007,45(11-12):1350-1362
This paper presents a new approach to the analysis of asymptotic stability of artificial neural networks (ANN) with multiple time-varying delays subject to polytope-bounded uncertainties. This approach is based on the Lyapunov–Krasovskii stability theory for functional differential equations and the linear matrix inequality (LMI) technique with the use of a recent Leibniz–Newton model based transformation without including any additional dynamics.Three examples with numerical simulations are used to illustrate the effectiveness of the proposed method. The first example considers the neural network with multiple time-varying delays, which may be seen as a particular case of the second example where it is subject to uncertainties and multiple time-varying delays. Finally, the third example analyzes the stability of the neural network with higher numbers of neurons subject to a single time-delay. The Hopf bifurcation theory is used to verify the stability of the system when the origin falls into instability in the bifurcation point. 相似文献
34.
Philippe Quevauviller Roberto Morabito 《Analytical and bioanalytical chemistry》1995,351(4-5):343-344
35.
36.
Reinaldo B. Arellano-Valle 《Journal of multivariate analysis》2005,96(1):93-116
A new class of multivariate skew-normal distributions, fundamental skew-normal distributions and their canonical version, is developed. It contains the product of independent univariate skew-normal distributions as a special case. Stochastic representations and other main properties of the associated distribution theory of linear and quadratic forms are considered. A unified procedure for extending this class to other families of skew distributions such as the fundamental skew-symmetric, fundamental skew-elliptical, and fundamental skew-spherical class of distributions is also discussed. 相似文献
37.
38.
Reinaldo B. Arellano-Valle Marc G. Genton 《Annals of the Institute of Statistical Mathematics》2010,62(2):363-381
We study conditions under which an invariance property holds for the class of selection distributions. First, we consider
selection distributions arising from two uncorrelated random vectors. In that setting, the invariance holds for the so-called
C{\cal{C}} -class and for elliptical distributions. Second, we describe the invariance property for selection distributions arising
from two correlated random vectors. The particular case of the distribution of quadratic forms and its invariance, under various
selection distributions, is investigated in more details. We describe the application of our invariance results to sample
variogram and covariogram estimators used in spatial statistics and provide a small simulation study for illustration. We
end with a discussion about other applications, for example such as linear models and indices of temporal/spatial dependence. 相似文献
39.
Julián Bravo-Castillero Ariel Ramírez-Torres Catherine García-Reimbert Raúl Guinovart-Díaz Reinaldo Rodríguez-Ramos 《Waves in Random and Complex Media》2020,30(4):593-613
ABSTRACT The asymptotic homogenization method is applied to complex dielectric periodic composites. An equivalence to coupled dielectric problems with real coefficients is shown. This is similar to a piezoelectric problem: an out-plane mechanical displacement and an in-plane electric potential establishing a correspondence principle. Closed-form formulas for the complex dielectric effective tensor in the case of a square array of circular inclusions embedded in a matrix are given. These formulas are written in terms of a real and symmetric matrix which facilitates the implementation of the computational scheme. We also get similar formulas for multilayered complex dielectric composites. The real closed-form formulas are advantageous for estimating gain and loss enhancement properties of active and passive composites in certain volume fraction intervals. Numerical computations are performed and the results are compared with other approaches showing the usefulness of the obtained formulas. This may be of interest in the context of metamaterials. 相似文献
40.
Cesati RR Dwyer G Jones RC Hayes MP Yalamanchili P Casebier DS 《Organic letters》2007,9(26):5617-5620
Recently developed copper-catalyzed coupling methodology has been applied to the synthesis of amino acid derived enamides. Bond formation proved to be strongly influenced by protection strategy and vinyl iodide substitution while tolerant of limited side chain functionality. Assessment of aminopeptidase activity revealed a preference for (E)-1,2-disubstituted constructs. 相似文献