Search results for "Variant"
showing 10 items of 1267 documents
Stochastic discretized learning-based weak estimation: a novel estimation method for non-stationary environments
2016
The task of designing estimators that are able to track time-varying distributions has found promising applications in many real-life problems.Existing approaches resort to sliding windows that track changes by discarding old observations. In this paper, we report a novel estimator referred to as the Stochastic Discretized Weak Estimator (SDWE), that is based on the principles of discretized Learning Automata (LA). In brief, the estimator is able to estimate the parameters of a time varying binomial distribution using finite memory. The estimator tracks changes in the distribution by operating a controlled random walk in a discretized probability space. The steps of the estimator are discre…
Rotation-invariant optical recognition of three-dimensional objects.
2008
An automatic method for rotation-invariant three-dimensional (3-D) object recognition is proposed. The method is based on the use of 3-D information contained in the deformed fringe pattern obtained when a grating is projected onto an object’s surface. The proposed method was optically implemented by means of a two-cycle joint transform correlator. The rotation invariance is achieved by means of encoding with the fringe pattern a single component of the circular-harmonic expansion derived from the target. Thus the method is invariant for rotations around the line of sight. The whole experimental setup can be constructed with simple equipment. Experimental results show the utility of the pro…
The J-invariant, Tits algebras and Triality
2012
In the present paper we set up a connection between the indices of the Tits algebras of a simple linear algebraic group $G$ and the degree one parameters of its motivic $J$-invariant. Our main technical tool are the second Chern class map and Grothendieck's $\gamma$-filtration. As an application we recover some known results on the $J$-invariant of quadratic forms of small dimension; we describe all possible values of the $J$-invariant of an algebra with orthogonal involution up to degree 8 and give explicit examples; we establish several relations between the $J$-invariant of an algebra $A$ with orthogonal involution and the $J$-invariant of the corresponding quadratic form over the functi…
Robust control of a Hammerstein model of DC/DC converters
2007
This paper deals with the robust control of a Hammerstein mathematical model of DC/DC converters, consisting of the nonlinear static characteristics of the converter followed by one of a few number of linear time- invariant models which describe the converter in the useful working range. One of these models is assumed as the nominal model of the system and the remaining models are used for describing the model uncertainty. Nominal behaviour is assured using H-2 optimal control method, Robust stability and behaviour are assured by imposing H-infin specifications. The closed loop control system consisting of the converter Hammerstein model and the robust controller is analyzed by means of sim…
Tra uomo e donna. "Varianti sul tema" e invarianti nella scrittura
2018
Vengono individuate diverse riscritture grassiane che appaiono lungo il corso di 15 anni, ma che non si pongono lungo un continuum evolutivo. Non se ne coglie infatti un mutare evidente di usi linguistici o di istanze etico-estetiche che giustifichino i successivi e nuovi testi. Non ci sono, in quindici anni di riscrittura e nonostante i cambiamenti profondi delle sensibilità sociali sul tema del gender, attualizzazioni o integrazioni di segmenti narrativi: la Grasso reitera sempre gli stessi fotogrammi, quasi con le stesse parole e facendo riemergere sempre le stesse sensazioni. La protagonista, Enrichetta/Ninetta, non ha vita autonoma fuori dall’effetto suscitato nell’autrice bambina. Anc…
La linguistique cognitive existe-t-elle ?
2009
International audience; La présente contribution est consacrée à la question du statut théorique et de la légitimité même de la notion de ‘linguistique cognitive'. Sont tout d'abord rappelées (§ 1) les conditions historiques d'émergence, aux Etats-Unis, des deux grands courants de la linguistique dite ‘cognitive' : la grammaire générative (qui s'inscrit dans le paradigme ‘computo-représentationnel symbolique' du cognitivisme classique) et les grammaires cognitives (se réclamant d'un paradigme ‘constructiviste'). Puis (§ 2) est défendue l'idée qu'une théorie linguistique ne saurait se dire ‘cognitive' si elle ne cherche pas à relier explicitement les significations et les concepts, ce qui co…
Invariant varieties of discontinuous vector fields
2004
We study the geometric qualitative behaviour of a class of discontinuous vector fields in four dimensions around typical singularities. We are mainly interested in giving the conditions under which there exist one-parameter families of periodic orbits (a result that can be seen as one analogous to the Lyapunov centre theorem). The focus is on certain discontinuous systems having some symmetric properties. We also present an algorithm which detects and computes periodic orbits.
On the variations of the Betti numbers of regular levels of Morse flows
2011
Abstract We generalize results in Cruz and de Rezende (1999) [7] by completely describing how the Betti numbers of the boundary of an orientable manifold vary after attaching a handle, when the homology coefficients are in Z, Q, R or Z p Z with p prime. First we apply this result to the Conley index theory of Lyapunov graphs. Next we consider the Ogasa invariant associated with handle decompositions of manifolds. We make use of the above results in order to obtain upper bounds for the Ogasa invariant of product manifolds.
Chaotic Scattering in the Gaussian Potential
1995
It is well known that general classical Hamiltonian dynamical systems have as a rule chaotic behaviour. By such a term one usually understands a sensitive dependence on initial conditions which manifests itself in the topology of phase space. For the most studied case of bounded motions this behaviour is detected, for example, by analysing the Poincare surfaces of section and by calculating Lyapunov characteristic exponents. The question then naturally arises of what are the effects of this complexity on the unbounded motions, i.e., on scattering phenomena. The signature of chaotic dynamics in these scattering regions of phase space has been the object of several papers appeared mainly in t…
Modulation of MHC Class II Determinants on Rat Langerhans Cells During Short Term Culture
1993
Epidermal Langerhans cells (LC) are regarded as the most peripheral outpost of the immune system. They play a pivotal role during the onset of an immune response in the skin. One of the principal functions of LC is reflected in their extraordinary potency to present antigen to high activation requiring naive T cells.