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1,317 research outputs found

Signatures of Classical Periodic Orbits on a Smooth Quantum System

Author: A. Bohigas
B. Eckhardt
D. Provost
D. Provost
D. Provost
D. Provost
Daniel Provost
E. B. Bogomolny
E. J. Heller
E. P. Wigner
M. A. M. Aguiar
M. Baranger
M. Baranger
M. Baranger
M. C. Gutzwiller
M. Hillery
M. V. Berry
M. V. Berry
R. Aurich
R. Dahlqvist
S. C. Creagh
Publication venue: 'American Physical Society (APS)'
Publication date: 09/05/1995
Field of study

Gutzwiller's trace formula and Bogomolny's formula are applied to a non--specific, non--scalable Hamiltonian system, a two--dimensional anharmonic oscillator. These semiclassical theories reproduce well the exact quantal results over a large spatial and energy range.Comment: 12 pages, uuencoded postscript file (1526 kb

arXiv.org e-Print Archive

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The Contested Politics of Environmental Rulemaking

Author: Gerber B
Provost C
Publication venue: 'Edward Elgar Publishing'
Publication date: 01/01/2020
Field of study

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UCL Discovery

On approximating the distribution of indefinite quadratic expressions in singular normal vectors

Author: Mohsenipour Akbar
Provost Serge B.
Publication venue: 'University of Tartu'
Publication date: 31/12/2011
Field of study

General representations of quadratic forms and quadratic expressions in singular normal vectors are given in terms of the difference of two positive definite quadratic forms and an independentlydistributed linear combination of normal random variables. Up to now, only special cases have been treated in the statistical literature. The densities of the quadratic forms are then approximated with gamma and generalized gamma density functions. A moment-based technique whereby the initial approximations are adjusted by means of polynomials is presented. Closed form and integral formulae are provided for the approximate density functions of the quadratic forms and quadratic expressions. A detailed step-by-step algorithm for implementing the proposed density approximation technique is also provided. Two numerical examples illustrate the methodology

Journals from University of Tartu

Polynomial expansions via embedded Pascal’s triangles

Author: Provost Serge B.
Ratemi Wajdi M.
Publication venue: 'University of Tartu'
Publication date: 31/12/2011
Field of study

An expansion is given for polynomials of the form (ω + λ1) · · ·(ω +λn). The coefficients of the resulting polynomials are related to their roots, and a system of equations that enables one to numericallydetermine the roots in terms of the coefficients is specified. The case where all the roots λi are equal is considered as well. A multinomial extension to polynomials of the form (x1+ · · · + xI )n is then provided. As it turns out, the coefficients of the monomials contained in the resulting polynomial expansion can be determined in terms of the coefficients of the monomials included in the expansion of (x1+ · · · + xI-1 )n  and the rows of embedded Pascal’s triangles of successive orders. An algorithm is provided for generating and concatenating these rows, with the particulars of its implementation by means of the symbolic computation software Mathematica being discussed as well. Potential applications of such expansions to combinatorics and genomics are also suggested

Journals from University of Tartu

Generalized r-Modes of the Maclaurin Spheroids

Author: B. J. Owen
G. H. Bryan
H. Bateman
J. L. Friedman
J. Papaloizou
J. Papaloizou
J. Provost
J. Provost
J. R. Ipser
James R. Ipser
L. Lindblom
Lee Lindblom
N. Andersson
S. Chandrasekhar
Publication venue: 'American Physical Society (APS)'
Publication date: 04/12/1998
Field of study

Analytical solutions are presented for a class of generalized r-modes of rigidly rotating uniform density stars---the Maclaurin spheroids---with arbitrary values of the angular velocity. Our analysis is based on the work of Bryan; however, we derive the solutions using slightly different coordinates that give purely real representations of the r-modes. The class of generalized r-modes is much larger than the previously studied `classical' r-modes. In particular, for each l and m we find l-m (or l-1 for the m=0 case) distinct r-modes. Many of these previously unstudied r-modes (about 30% of those examined) are subject to a secular instability driven by gravitational radiation. The eigenfunctions of the `classical' r-modes, the l=m+1 case here, are found to have particularly simple analytical representations. These r-modes provide an interesting mathematical example of solutions to a hyperbolic eigenvalue problem.Comment: 12 pages, 3 figures; minor changes and additions as will appear in the version to be published in Physical Review D, January 199

arXiv.org e-Print Archive

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On the Distribution of the Peña Rodríguez Portmanteau Statistic

Author: Deepak Sanjel
Serge B. Provost
Susan Z. Sheng
Publication venue: 'Pakistan Journal of Statistics and Operation Research'
Publication date: 01/07/2012
Field of study

<p class="MsoNormal" style="text-align: justify;"><span style="font-size: 10pt;">Peña and Rodríguez (2002) introduced a portmanteau test for time series which turns out to be more powerful than those proposed by Ljung and Box (1986) and Monti (1994), and approximated its distribution by means of a two-parameter gamma random variable. A polynomially adjusted beta approximation is proposed in this paper. This approximant is based on the moments of the statistic, which can be estimated by simulation or determined by symbolic computations or numerical integration. Various types of time series processes such as AR(1), MA(1), ARMA<span>(2,2) </span>are being considered. The proposed approximation turns out to be nearly exact.</span></p

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Pakistan Journal of Statistics and Operation Research

Asymptotic and measured large frequency separations

Author: Auvergne M.
Baglin A.
Barban C.
Belkacem K.
Catala C.
Goupil M. J.
Michel E.
Mosser B.
Provost J.
Samadi R.
Publication venue: 'EDP Sciences'
Publication date: 02/01/2013
Field of study

With the space-borne missions CoRoT and Kepler, a large amount of asteroseismic data is now available. So-called global oscillation parameters are inferred to characterize the large sets of stars, to perform ensemble asteroseismology, and to derive scaling relations. The mean large separation is such a key parameter. It is therefore crucial to measure it with the highest accuracy. As the conditions of measurement of the large separation do not coincide with its theoretical definition, we revisit the asymptotic expressions used for analysing the observed oscillation spectra. Then, we examine the consequence of the difference between the observed and asymptotic values of the mean large separation. The analysis is focused on radial modes. We use series of radial-mode frequencies to compare the asymptotic and observational values of the large separation. We propose a simple formulation to correct the observed value of the large separation and then derive its asymptotic counterpart. We prove that, apart from glitches due to stellar structure discontinuities, the asymptotic expansion is valid from main-sequence stars to red giants. Our model shows that the asymptotic offset is close to 1/4, as in the theoretical development. High-quality solar-like oscillation spectra derived from precise photometric measurements are definitely better described with the second-order asymptotic expansion. The second-order term is responsible for the curvature observed in the \'echelle diagrams used for analysing the oscillation spectra and this curvature is responsible for the difference between the observed and asymptotic values of the large separation. Taking it into account yields a revision of the scaling relations providing more accurate asteroseismic estimates of the stellar mass and radius.Comment: accepted in A&

arXiv.org e-Print Archive

HAL - Normandie Université

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Effects of Transceiver Jitter on the Performance of Optical Scattering Communication Systems

Author: Ma Jianshe
Provost Serge B.
Shen Zanqiu
Su Ping
Publication venue
Publication date: 02/02/2024
Field of study

In ultraviolet communications, the transceiver jitter effects have been ignored in previous studies, which can result in non-negligible performance degradation especially in vibration states or in mobile scenes. To address this issue, we model the relationship between the received power and transceiver jitter by making use of a moment-based density function approximation method. Based on this relationship, we incorporate the transceiver jitter effects in combination with Poisson distribution. The error rate results are obtained assuming on-off key modulation with optimal threshold based detection. We validate the error rate expressions by comparing the analytical results with Monte-Carlo simulation results. The results show that the transceiver jitter effects cause performance degradation especially in smaller transceiver elevation angles or in shorter distances, which are often adopted in short-range ultraviolet communications. The results also show that larger elevation angle cases have a better performance with respect to anti-jitter and may perform better compared to smaller elevation angle situations in the case of larger standard deviation of jitter. This work studies for the first time the transceiver jitter effects in ultraviolet communications and provides guidelines for experimental system design.Comment: 5 pages, 2 figures, comments are welcome

arXiv.org e-Print Archive