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Your search keyword '"Oliveira, Amílcar"' showing total 2 results
Start Over Author "Oliveira, Amílcar" Topic density functional theory
2 results on '"Oliveira, Amílcar"'

1. The uniform distribution product: an approach to the (Q,r) inventory model using R.

Author

Oliveira, Amílcar, Oliveira, Teresa, and Seijas-Macías, Antonio

Subjects
*PROBABILITY theory, *RANDOM variables, *DENSITY functionals, *DENSITY functional theory, *MATHEMATICAL models
Abstract

In this work the probability density function (PDF) for the product of two uniformly distributed random variables is explored under the implementation of a new procedure in R language. Based on the Rohatgi theorem for the theoretical form of the product, different possibilities for the range of values of the limits of both distributions are considered. As an application, the management of a inventory model with the presence of lead-time and uniform demand forecasts is considered. Solution to this model looks up to minimize the total costs through the variables Q (reorder quantity) and r (the reorder point), and not always exists an analytical solution of the problem. We show a graphical procedure for the simulation results and a more exactly analytical solution. Implementation in R is straightforward. [ABSTRACT FROM AUTHOR]

Published
2018
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2. Distribution Function for the ratio of Two Normal Random Variables.

Author

Oliveira, Amílcar, Oliveira, Teresa, Macías, Seijas, and Antonio

Subjects
*DISTRIBUTION (Probability theory), *RANDOM variables, *DENSITY functional theory, *APPROXIMATION theory, *STANDARD deviations
Abstract

The distribution of the ratio of two normal random variables X and Y was studied from [1] (the density function) and [2] (the distribution function). The shape of its density function can be uni-modal, bimodal, symmetric, asymmetric, following several type of distributions, like Dirac Distribution, Normal Distribution, Cauchy Distribution or Recinormal Distribution. In this paper we study a different approximation for this distribution Z = X/Y, as a function of four parameters: ratio of the means of the two normal variables, ratio of the standard deviations of the two normal variables, the variation coefficient of the normal variable Y, and the correlation between the two variables. A formula for the Distribution function and the density function of Z is given. In addition, using graphical procedures we established singularity points for the parameters where the approximation given for Z has a non normal shape. [ABSTRACT FROM AUTHOR]

Published
2015
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