Search results for "Quadrat"

Robust and Model Predictive Control applied to DC/DC converters and Shunt Active Filters

Al giorno d'oggi, la domanda di energia elettrica incrementa giorno per giorno. La gente spesso la usa con superficialità sottovalutando quanto essa sia preziosa. Fino a qualche decennio fa, la generazione di energia elettrica era centralizzata e dipendeva dallo sfruttamento delle risorse fossili. La limitatezza delle fonti fossili, insieme agli effetti ambientali del loro sfruttamento, hanno portato la ricerca a trovare vettori energetici alternativi poco inquinanti e facilmente reperibili. Lo sviluppo e la diffusione delle fonti energetiche rinnovabili hanno sancito la fine di una rete elettrica centralizzata a favore di una nuova idea di rete elettrica di tipo distribuita che permette di…

Le "Choral-Variationen" Bach-Stravinsky per la basilica di San Marco: simbologia e Quadrato magico

2020

Eseguite per la prima volta nella basilica di San Marco il 13 settembre 1956, le Choral-Variationen uber das Weinachtslied “Vom Himmel hoch...” (1955-56) di Stravinsky sono una reinvenzione originale e creativa delle Canonische Veränderungen BWV 796 di J.S. Bach, che presenta una profonda relazione con la struttura architettonica e i simboli della basilica, ma anche - in maniera più segreta - con il quadrato magico SATOR / AREPO / TENET / OPERA / ROTAS and e con la musica di Anton Webern. First performed in the Basilica of St. Mark on 13th September 1956, Stravinky’s Choral Variations on the Christmas Carol “Vom Himmel hoch...” (1955-56) are an original and creative reinvention of the Canon…

Random Stability of an Additive-Quadratic-Quartic Functional Equation

2010

Using the fixed point method, we prove the generalized Hyers-Ulam stability of the following additive-quadratic-quartic functional equation f(x+2y)+f(x−2y)=2f(x+y)+2f(−x−y)+2f(x−y)+2f(y−x)−4f(−x)−2f(x)+f(2y)+f(−2y)−4f(y)−4f(−y) in complete random normed spaces.

Local Splines on Non-uniform Grid

2018

In this Chapter and in the next Chap. 7, we deal with continuous rather than discrete and discrete-time splines. In these and only these chapters, we abandon the assumption that the grid, on which the splines are constructed, is uniform and consider splines on arbitrary grids. Two types of local cubic and quadratic splines on non-uniform grids are described: 1. The simplest variation-diminishing splines and 2. The quasi-interpolating splines. The splines are computed by simple fast computational algorithms that utilize relations between the splines and interpolation polynomials. In addition, these relations provide sharp estimations of splines’ approximation accuracy. These splines can serv…

Adaptive quadratic regularization for baseline wandering removal in wearable ECG devices

2016

The electrocardiogram (ECG) is one of the most important physiological signals to monitor the health status of a patient. Technological advances allow the size and weight of ECG acquisition devices to be strongly reduced so that wearable systems are now available, even though the computational power and memory capacity is generally limited. An ECG signal is affected by several artifacts, among which the baseline wandering (BW), i.e., a slowly varying variation of its trend, represents a major disturbance. Several algorithms for BW removal have been proposed in the literature. In this paper, we propose new methods to face the problem that require low computational and memory resources and th…

The Tan 2Θ Theorem in fluid dynamics

2017

We show that the generalized Reynolds number (in fluid dynamics) introduced by Ladyzhenskaya is closely related to the rotation of the positive spectral subspace of the Stokes block-operator in the underlying Hilbert space. We also explicitly evaluate the bottom of the negative spectrum of the Stokes operator and prove a sharp inequality relating the distance from the bottom of its spectrum to the origin and the length of the first positive gap.

Block-Based Inversion of the Heat Equations

2014

This chapter presents robust methods, which refine the algorithms, in Sect. 7.2, for inversion of the heat equations. The idea behind the algorithms is to solve the inversion problem separately in different frequency bands. This is achieved by using spline wavelet packets. The solutions that minimize some parameterized quadratic functionals, are derived as linear combinations of the wavelet packets. Choice of parameters, which is performed automatically, determines the trade-off between the solution regularity and the initial data approximation. The Spline Harmonic Analysis (SHA) technique provides a unified computational scheme for the fast implementation of the algorithm and an explicit r…

Solving some optimal control problems using the barrier penalty function method

2005

In this paper we present a new approach to solve the two-level optimization problem arising from an approximation by means of the finite element method of optimal control problems governed by unilateral boundary value problems. The minimized functional depends on control variables and state variables x. The latter are the optimal solution of an auxiliary quadratic programming problem, whose parameters depend on u.

Parasite infracommunities as predictors of harvest location of bogue (Boops boops L.): a pilot study using statistical classifiers

2005

The accuracy of classifying bogue (Boops boops) according to the fishery from which it was harvested was evaluated by applying several statistical classification techniques to fish parasite abundances. Bogue captured in 2001 in two fisheries off the Atlantic coast of Spain were compared with one off the Spanish Mediterranean coast. One hundred bogue were classified to each harvest location (fishery) using different numbers of parasite species chosen as predictors by a best subset method. Two parametric methods of classification (linear and quadratic discriminant analysis) were compared with two non-parametric approaches (k-nearest neighbour classification and feed-forward neural network) an…

Statistics of nonlinear stochastic dynamical systems under Lévy noises by a convolution quadrature approach

2010

This paper describes a novel numerical approach to find the statistics of the non-stationary response of scalar non-linear systems excited by L\'evy white noises. The proposed numerical procedure relies on the introduction of an integral transform of Wiener-Hopf type into the equation governing the characteristic function. Once this equation is rewritten as partial integro-differential equation, it is then solved by applying the method of convolution quadrature originally proposed by Lubich, here extended to deal with this particular integral transform. The proposed approach is relevant for two reasons: 1) Statistics of systems with several different drift terms can be handled in an efficie…