Search results for "Mathematica"

SIOPRED performance in a Forecasting Blind Competition

2012

In this paper we present the results obtained by applying our automatic forecasting support system, named SIOPRED, over a data set of time series in a Forecasting Blind Competition. In order to apply our procedure for providing point forecasts it has been necessary to develop an interactive strategy for the choice of the suitable length of the seasonal cycle and the seasonality form for a generalized exponential smoothing method, which have been obtained using SIOPRED. For the choice of those essential characteristics of forecasting methods, also a certain multi-objective formulation which minimizes several measures of fitting is used. Once these specifications are established, the model pa…

Soft Computing Techniques for Portfolio Selection: Combining SRI with Mean-Variance Goals

2014

A fuzzy portfolio selection model is presented incorporating a socially responsible goal without discarding a priori financially good portfolios or weakening a priori the financial goals. Hence, the optimal portfolios it provides could be either efficient from the strictly financial point of view or non-efficient if leaving the efficient frontier substantially improves the degree of social responsibility. The model can be used to direct heuristic procedures in order to select a reduced number of various alternatives from which the investor can directly make a final decision.

Multi-Skill Call Center as a Grading from “Old” Telephony

2009

We explore parallels between the older telephony switches and the multi-skill call centers. The numerical results have shown that a call center with equally distributed skills is preferable compared to traditional grading-type design. The annex contains a short version of mathematical proof on limited availability schemes design for small call flow intensity *** and for large *** . The proof explores one excellent V. Benes' paper (from Bell Labs). On its own merit, the annex could initiate new mathematical research in call center area, more by now the powerful software for numerical analysis is available. Main conclusion is the following: numerical analysis of simple multi-skill call center…

PyCellBase

2019

Python package for easy retrieval of biological data from heterogeneous sources.

Numerical study of soliton stability, resolution and interactions in the 3D Zakharov–Kuznetsov equation

2021

International audience; We present a detailed numerical study of solutions to the Zakharov-Kuznetsov equation in three spatial dimensions. The equation is a three-dimensional generalization of the Korteweg-de Vries equation, though, not completely integrable. This equation is L-2-subcritical, and thus, solutions exist globally, for example, in the H-1 energy space.We first study stability of solitons with various perturbations in sizes and symmetry, and show asymptotic stability and formation of radiation, confirming the asymptotic stability result in Farah et al. (0000) for a larger class of initial data. We then investigate the solution behavior for different localizations and rates of de…

Numerical study of blow-up and stability of line solitons for the Novikov-Veselov equation

2017

International audience; We study numerically the evolution of perturbed Korteweg-de Vries solitons and of well localized initial data by the Novikov-Veselov (NV) equation at different levels of the 'energy' parameter E. We show that as |E| -> infinity, NV behaves, as expected, similarly to its formal limit, the Kadomtsev-Petviashvili equation. However at intermediate regimes, i.e. when |E| is not very large, more varied scenarios are possible, in particular, blow-ups are observed. The mechanism of the blow-up is studied.

Zero viscosity limit of the Oseen equations in a channel

2001

Oseen equations in the channel are considered. We give an explicit solution formula in terms of the inverse heat operators and of projection operators. This solution formula is used for the analysis of the behavior of the Oseen equations in the zero viscosity limit. We prove that the solution of Oseen equations converges in W1,2 to the solution of the linearized Euler equations outside the boundary layer and to the solution of the linearized Prandtl equations inside the boundary layer. © 2001 Society for Industrial and Applied Mathematics.

ON THE ONE-DIMENSIONAL SCHRÖDINGER EQUATION WITH A QUASI-PERIODIC POTENTIAL

1980

Modified Landau levels, damped harmonic oscillator and two-dimensional pseudo-bosons

2010

In a series of recent papers one of us has analyzed in some details a class of elementary excitations called {\em pseudo-bosons}. They arise from a special deformation of the canonical commutation relation $[a,a^\dagger]=\1$, which is replaced by $[a,b]=\1$, with $b$ not necessarily equal to $a^\dagger$. Here, after a two-dimensional extension of the general framework, we apply the theory to a generalized version of the two-dimensional Hamiltonian describing Landau levels. Moreover, for this system, we discuss coherent states and we deduce a resolution of the identity. We also consider a different class of examples arising from a classical system, i.e. a damped harmonic oscillator.

Intramolecular Dipole Reorientation of Amino Compounds and their Interaction with Solvent Molecules. I

1972

Abstract The dielectric absorption of dilute solutions of aniline, methyl substituted anilines, chlorine substituted anilines, N,N,N',N'-tetramethyl-p-phenylene diamine and 4-aminobiphenyl in various sol-vents has been measured between 0.3 and 135 GHz. The measurements have been carried out at 20 °C and for some mesitylene solutions also at -30 °C and 60 °C. The absorption curves have been resolved into multiple absorption regions. A far infrared (FIR) term had to be included in each analysis. Its contribution to the total dipole reorientation depends on the solvent and on the mobility of the substituted groups in the phenyl ring. The obtained group relaxation times are longer than those re…