Search results for "LYN"
showing 10 items of 910 documents
Codimensions of algebras and growth functions
2008
Abstract Let A be an algebra over a field F of characteristic zero and let c n ( A ) , n = 1 , 2 , … , be its sequence of codimensions. We prove that if c n ( A ) is exponentially bounded, its exponential growth can be any real number >1. This is achieved by constructing, for any real number α > 1 , an F-algebra A α such that lim n → ∞ c n ( A α ) n exists and equals α. The methods are based on the representation theory of the symmetric group and on properties of infinite Sturmian and periodic words.
A fully adaptive multiresolution scheme for image processing
2007
A nonlinear multiresolution scheme within Harten's framework [A. Harten, Discrete multiresolution analysis and generalized wavelets, J. Appl. Numer. Math. 12 (1993) 153-192; A. Harten, Multiresolution representation of data II, SIAM J. Numer. Anal. 33 (3) (1996) 1205-1256] is presented. It is based on a centered piecewise polynomial interpolation fully adapted to discontinuities. Compression properties of the multiresolution scheme are studied on various numerical experiments on images.
Indefinite integrals of special functions from inhomogeneous differential equations
2018
A method is presented for deriving integrals of special functions which obey inhomogeneous second-order linear differential equations. Inhomogeneous equations are readily derived for functions sati...
Non-stationarity tests and nonlinear trends
1992
This paper stresses the importance of the hypothesis of linearity of the deterministic component imposed by unit root testing procedures most frequently used in empirical literature. We suggest an empirical testing strategy which reduces the risk of reaching false conclusions due to the misspecification of that component and we apply it to the analysis of the nonstationarity exhibited by real GNP in France. We show that it is possible to find someflexible specifications which enable us to reject the unit root null hypothesis otherwise strongly supported in empirical literature. These specifications might be considered as approximations of the true process generating real GNP and might be us…
Construction of a fundamental set of solutions of an arbitrary homogeneous linear difference equation
2002
Abstract The detailed construction of a prefixed fundamental set of solutions of a linear homogeneous difference equation of any order with arbitrarily variable coefficients is reported. The usefulness of the resulting resolutive formula is illustrated by simple applications to the Hermite polynomials and to the Fibonacci sequence.
Identification of linear parameter varying models
2002
We consider identification of a certain class of discrete-time nonlinear systems known as linear parameter varying system. We assume that inputs, outputs and the scheduling parameters are directly measured, and a form of the functional dependence of the system coefficients on the parameters is known. We show how this identification problem can be reduced to a linear regression, and provide compact formulae for the corresponding least mean square and recursive least-squares algorithms. We derive conditions on persistency of excitation in terms of the inputs and scheduling parameter trajectories when the functional dependence is of polynomial type. These conditions have a natural polynomial i…
8000 years of coastal changes on a western Mediterranean island: A multiproxy approach from the Posada plain of Sardinia
2018
Abstract A multi-proxy palaeoenvironmental investigation was conducted to reconstruct the Holocene history of coastal landscape change in the lower Posada coastal plain of eastern Sardinia. In the Mediterranean region, coastal modifications during the Holocene have been driven by a complex interplay between climate, geomorphological processes and human activity. In this paper, millennial-scale human-sea level-environment interactions are investigated near Posada, one of the largest coastal plains in eastern Sardinia. Biostratigraphic and palynological approaches were used to interpret the chrono-stratigraphy exhibited by a series of new cores taken from the coastal plain. This new study elu…
Late Holocene Aleppo pine (Pinus halepensis Miller) woodlands in Mallorca (Balearic Islands, Western Mediterranean): Investigation of their distribut…
2021
The pioneering nature of Mediterranean pines and their phytosociological role have been largely discussed in relation to different agents (e.g., edaphic, climatic or anthropogenic). In this context, Aleppo pine is one of the most widespread pine species in the Mediterranean basin, as it is especially adapted to climatic constraints, such as drought and high seasonality, and has a high tolerance for salinity and strong coastal winds. It is also well adapted to regeneration after anthropogenic landscape disturbances, highlighting its important after-fire regeneration rates. In this sense, phytosociological studies conducted in Mediterranean landscapes have found that this species' wide distri…
The Grotta Grande of Scario (Salerno, Italy): Archaeology and environment during the last interglacial (MIS 5) of the Mediterranean region
2011
Abstract Archeological and paleo-environmental researches carried on the Grotta Grande site illustrate the importance of a multidisciplinary approach among archeologists, palynologists and paleontologists. The archaeology, fauna, pollen and micro-charcoal recovered in two short sedimentary successions (trenches A, F) located close to the entrance of the cave are discussed. The cave opens directly on the Tyrrhenian Sea, 2 km from Scario (Salerno, Campania, Southern Italy). The morphology of the cave and sedimentary processes were controlled by eustatic fluctuations during the late Middle Pleistocene and the early Late Pleistocene. The sea repeatedly occupied the cave. The cave was frequented…
The MIS 5 palaeoenvironmental record in the SE Mediterranean coast of the Iberian Peninsula (Río Antas, Almería, Spain)
2015
Se realiza un estudio detallado del episodio cálido MIS 5 en la zona sureste de la Península Ibérica. Se realiza la reconstrucción paleoambiental a partir del estudio polínico y biomarcadores de un sondeo perforado en la costa de Almería. La cronología se estableció a partir del método de racemizaciónd e aminoácidos.Landwards of a MIS5 bar, a borehole core (SRA) was analyzed to establish the relationship between the lagoonal record and the raised beach deposits in the surroundings of the Antas river mouth and to reconstruct the Pleistocene palaeoenvironmental evolution 5 of the southern Mediterranean coast of the Iberian Peninsula. 63 samples were recovered for amino acid racemization datin…