924 resultados para Multivariable polynomials
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Measurements of global and diffuse solar-radiation, at the Earth's surface, carried out from May 1994 to June 1999 in São Paulo City, Brazil, were used to develop correlation models to estimate hourly, daily and monthly values of diffuse solar-radiation on horizontal surfaces. The polynomials derived by linear regression fitting were able to model satisfactorily the daily and monthly values of diffuse radiation. The comparison with models derived for other places demonstrates some differences related mainly to altitude effects. (C) 2002 Elsevier B.V. Ltd. All rights reserved.
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Two applications of the modified Chebyshev algorithm are considered. The first application deals with the generation of orthogonal polynomials associated with a weight function having singularities on or near the end points of the interval of orthogonality. The other application involves the generation of real Szego polynomials.
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In this paper we prove that the set of equivalence classes of germs of real polynomials of degree less than or equal to k, with respect to K-bi-Lipschitz equivalence, is finite.
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Some polynomials and interpolatory quadrature rules associated with strong Stieltjes distributions are considered, especially when the distributions satisfy a Certain symmetric property. (C) 1995 Academic Press, Inc.
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The results in this paper are motivated by two analogies. First, m-harmonic functions in R(n) are extensions of the univariate algebraic polynomials of odd degree 2m-1. Second, Gauss' and Pizzetti's mean value formulae are natural multivariate analogues of the rectangular and Taylor's quadrature formulae, respectively. This point of view suggests that some theorems concerning quadrature rules could be generalized to results about integration of polyharmonic functions. This is done for the Tchakaloff-Obrechkoff quadrature formula and for the Gaussian quadrature with two nodes.
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We carry out a numerical and analytic analysis of the Yang-Lee zeros of the ID Blume-Capel model with periodic boundary conditions and its generalization on Feynman diagrams for which we include sums over all connected and nonconnected rings for a given number of spins. In both cases, for a specific range of the parameters, the zeros originally on the unit circle are shown to depart from it as we increase the temperature beyond some limit. The curve of zeros can bifurcate- and become two disjoint arcs as in the 2D case. We also show that in the thermodynamic limit the zeros of both Blume-Capel models on the static (connected ring) and on the dynamical (Feynman diagrams) lattice tend to overlap. In the special case of the 1D Ising model on Feynman diagrams we can prove for arbitrary number of spins that the Yang-Lee zeros must be on the unit circle. The proof is based on a property of the zeros of Legendre polynomials.
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In the present work, we expanded the study done by Solorzanol(1) including the eccentricity of the perturbing body. The assumptions used to develop the single-averaged analytical model are the same ones of the restricted elliptic three-body problem. The disturbing function was expanded in Legendre polynomials up to fourth-order. After that, the equations of motion are obtained from the planetary equations and we performed a set of numerical simulations. Different initial eccentricities for the perturbing and perturbed body are considered. The results obtained perform an analysis of the stability of a near-circular orbits and investigate under which conditions this orbit remain near-circular.
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The inappropriate use of antimicrobials in hospitals presents a negative impact on patient outcome and is associated with the emergence and spread of multidrug-resistant microorganisms. Antimicrobial stewardship programs (ASPs) have been instituted in order to improve the quality of prescriptions in hospitals. In this setting, the identification of patterns of inappropriate antimicrobial prescription is a valuable tool that allows ASPs to identify priorities for directing educative/restrictive policies. With this purpose, a study was conducted in the Bauru State Hospital, a teaching hospital with 285 beds affiliated to the Botucatu Medical School, São Paulo State University. The hospital maintains an active ASP since it was opened, in 2002. We selected 25% of the requests for parenteral antimicrobials (RPAs) from 2005 for analysis. Prescriptions for prophylactic purposes were excluded. All other RPAs were classified according to a modified Kunin and Jones categories. Univariate and multivariable analyses were performed to identify predictors of general inappropriateness and of specific prescription errors. Prescriptions classified as "appropriate'' or "probably appropriate" were selected as controls in all stages of the study. Among 963 RPAs included in our study, 34.6% were inappropriate. General predictors of inappropriateness were: prescription on weekends/holidays (OR = 1.67, 95% CI = 1.20-2.28, p = 0.002), patient from intensive care unit (OR = 1.57, 95% CI = 1.11-2.23, p = 0.01), peritoneal (OR = 2.15, 95% CI = 1.27-3.65, p = 0.004) or urinary tract infection (OR = 1.89, 95% CI = 1.25-2.87, p = 0.002), combined therapy with two or more antimicrobials (OR = 1.72, 95% CI = 1.15-2.57, p = 0.008) and prescriptions including penicillin (OR = 2.12, 95% CI = 1.39-3.25, p = 0.001) or first-generation cephalosporins (OR = 1.74, 95% CI = 1.01-3.00, p = 0.048). Previous consultation with an infectious diseases (ID) specialist had a protective effect against inappropriate prescription (OR = 0.34, 95% CI = 0.24-0.50, p < 0.001). Factors independently associated with specific prescription errors varied. However, consultation with an ID specialist was protective against both unnecessary antimicrobial use (OR = 0.04, 95% CI = 0.01-0.26, p = 0.001) and requests for agents with insufficient spectrum (OR = 0.14, 95% CI = 0.03-0.30, p = 0.01). In conclusion, the analysis of factors predictive of inappropriateness in antimicrobial prescription allowed us to identify issues requiring intervention. Also, it provided a positive feedback of the ASP efficacy, demonstrating the importance of previous consultation with an ID specialist to assure the quality of antimicrobial prescriptions.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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We prove a relation between two different types of symmetric quadrature rules, where one of the types is the classical symmetric interpolatory quadrature rules. Some applications of a new quadrature rule which was obtained through this relation are also considered.
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Piecewise-Linear Programming (PLP) is an important area of Mathematical Programming and concerns the minimisation of a convex separable piecewise-linear objective function, subject to linear constraints. In this paper a subarea of PLP called Network Piecewise-Linear Programming (NPLP) is explored. The paper presents four specialised algorithms for NPLP: (Strongly Feasible) Primal Simplex, Dual Method, Out-of-Kilter and (Strongly Polynomial) Cost-Scaling and their relative efficiency is studied. A statistically designed experiment is used to perform a computational comparison of the algorithms. The response variable observed in the experiment is the CPU time to solve randomly generated network piecewise-linear problems classified according to problem class (Transportation, Transshipment and Circulation), problem size, extent of capacitation, and number of breakpoints per arc. Results and conclusions on performance of the algorithms are reported.
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A simple procedure to obtain complete, closed expressions for Lie algebra invariants is presented. The invariants are ultimately polynomials in the group parameters. The construction of finite group elements requires the use of projectors, whose coefficients are invariant polynomials. The detailed general forms of these projectors are given. Closed expressions for finite Lorentz transformations, both homogeneous and inhomogeneous, as well as for Galilei transformations, are found as examples.
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The main purpose of this paper is to investigate theoretically and experimentally the use of family of Polynomial Powers of the Sigmoid (PPS) Function Networks applied in speech signal representation and function approximation. This paper carries out practical investigations in terms of approximation fitness (LSE), time consuming (CPU Time), computational complexity (FLOP) and representation power (Number of Activation Function) for different PPS activation functions. We expected that different activation functions can provide performance variations and further investigations will guide us towards a class of mappings associating the best activation function to solve a class of problems under certain criteria.
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The polynomials occurring in the wave functions of hydrogenic excited states are found to present difficulties for a straightforward analytical approach to the study of associated information entropies. A method is suggested to deal with them. It is then applied to calculate the information entropy for the Jacobi polynomial. A model calculation is presented to examine the effect of screening on the entropy sum. It is seen that the sum does not depend on the choice of screening.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)