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Pascal Alain Dkengne Sielenou

Pascal Alain Dkengne Sielenou
National Institute for Research in Digital Science and Technology (INRIA)

PhD

About

31
Publications
7,734
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193
Citations

Publications

Publications (31)
Article
Full-text available
Remarkable episodes of avalanche events, so-called snow avalanche cycles, are recurring threats to people and infrastructures in mountainous areas. This study focuses on the hazard assessment of snow avalanche cycles defined by daily occurrence numbers exceeding the 2-year return level. To this aim, extreme value distributions are tailored to accou...
Article
Determining avalanche activity corresponding to given snow and meteorological conditions is an old problem of high practical relevance. To address it, numerous statistical forecasting models have been developed, but intercomparisons of their efficiency on very large datasets are seldom. In this work, an approach combining random forests with class-...
Preprint
Full-text available
The block maxima approach is one of the main methodologies in extreme value theory to obtain a suitable distribution to estimate the probability of large values. In this approach, the block size is usually selected in order to reflect the possible intrinsic periodicity of the studied phenomenon. The generalization of this approach to data from non-...
Conference Paper
Full-text available
In the last decade digital media: web or app publishers, generalised the use of real-time ad auctions to sell their ad-spaces. Multiple auction platforms, also called Supply Side Platforms (SSP) were created. Because of this multiplicity, publishers started to create competition between SSPs. In this setting, there are two successive auctions: a se...
Preprint
Full-text available
Over the last decade, digital media (web or app publishers) generalized the use of real time ad auctions to sell their ad spaces. Multiple auction platforms, also called Supply-Side Platforms (SSP), were created. Because of this multiplicity, publishers started to create competition between SSPs. In this setting, there are two successive auctions:...
Article
Full-text available
Recent record-breaking glacier melt values are attributable to peculiar extreme events and long-term warming trends that shift averages upwards. Analyzing one of the world's longest mass-balance series with extreme value statistics, we show that detrending melt anomalies makes it possible to disentangle these effects, leading to a fairer evaluation...
Article
The eruption of Samalas in Indonesia in 1257 ranks among the largest sulfur-rich eruptions of the Common Era with sulfur deposition in ice cores reaching twice the volume of the Tambora eruption in 1815. Sedimentological analyses of deposits confirm the exceptional size of the event, which had both an eruption magnitude and a volcanic explosivity i...
Article
Full-text available
In this paper, we generalize earlier work dealing with maxima of discrete random variables. We show that row-wise stationary block maxima of a triangular array of integer valued random variables converge to a Gumbel extreme value distribution if row-wise variances grow sufficiently fast as the row-size increases. As a by-product, we derive analytic...
Preprint
Full-text available
Lecture notes on differential equations
Thesis
Full-text available
This work substantially deals with our contribution to the theory of nonlinear systems of partialdifferential equations and variational calculus.Direct methods and symmetry analysis for investigation of analytical exact or approximate solutions of linear as well as nonlinear models are performed. We start by presenting the factorization method for...
Article
Full-text available
In this paper, we propose some algorithms for analytical solution construction to nonlinear polynomial partial differential equations with constant function coefficients. These schemes are based on one-(single), two- (double) or three- (triple) function expansion methods. Most of the existing expansion function methods are well recovered from the m...
Article
Full-text available
This paper addresses both necessary and relevant sufficient extremum conditions for a variational problem defined by a smooth Lagrangian, involving higher derivatives of several variable vector valued functions. A general formulation of first order necessary extremum conditions for variational problems with (or without) constraints is given. Global...
Article
Full-text available
An algebraic approach for factorizing nonlinear partial differential equations (PDEs) and systems of PDEs is provided. In the particular case of second order linear and nonlinear PDEs and systems of PDEs, necessary and sufficient conditions of factorization are given.
Article
In this paper, the Adomian decomposition method for solving nonlinear partial differential equations (NPDEs) is revisited. Then we show how this method can be extended and used to solve under-determined systems of NPDEs. The examples of Kompaneets, Novikov and Ginzburg-Landau equations are considered as illustration.
Article
Full-text available
This work extends the Ibragimov's conservation theorem for partial differential equations [{\it J. Math. Anal. Appl. 333 (2007 311-328}] to under determined systems of differential equations. The concepts of adjoint equation and formal Lagrangian for a system of differential equations whose the number of equations is equal to or lower than the numb...
Article
Full-text available
We prove both necessary and sufficient second order conditions of extrema for variational problems involving any higher order continuously twice differentiable Lagrangians with multi-valued dependent functions of several variables. Our analysis is performed in the framework of the finite dimensional total jet space.
Article
Full-text available
This paper addresses necessary and sufficient factorizability condi-tions for classes of second order linear ordinary differential equations (ODEs) characterized by the degrees of their corresponding polynomial functions coef-ficients. A pure algebraic method is used to solve a system of linear algebraic equations whose solutions satisfy a compatib...
Article
In this paper, we propose an alternative direct algebraic method of constructing, for nonlinear evolution partial differential equations, conservation laws that depend not only on dependent variables and its derivatives but also explicitly on independent variables. As illustration, the fifth order Korteweg de Vries (fKdV) and modified $(n+1)$-dimen...
Article
This work addresses an algebraic method of factorizing linear and nonlinear ordinary differential equations (ODEs). Systems of ODEs are probed. Concrete examples are also treated.
Article
Full-text available
The method of parameter variation for linear differential equations is extended to classes of second order nonlinear differential equations. This allows to reduce the latter to first order differential equations. Known classical equations such as the Bernoulli, Riccati and Abel equations are recovered in illustrated relevant examples.
Article
The Lie symmetry reduction of the fifth order Korteweg de Vries equations with respect to an optimal set of one-dimensional subgroups of its full symmetry Lie group is carried out. New classes of exact solutions of the investigated equations are found by applying to the reduced equations a direct algebraic method based on an extended classification...

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