INFFTM: Fast evaluation of 3d Fourier series in MATLAB with an application to quantum vortex reconnections

Although Fourier series approximation is ubiquitous in computational physics owing to the Fast Fourier Transform (FFT) algorithm, efficient techniques for the fast evaluation of a three-dimensional truncated Fourier series at a set of \emph{arbitrary} points are quite rare, especially in MATLAB language. Here we employ the Nonequispaced Fast Fourier Transform (NFFT, by J. Keiner, S. Kunis, and D. Potts), a C library designed for this purpose, and provide a Matlab and GNU Octave interface that makes NFFT easily available to the Numerical Analysis community. We test the effectiveness of our package in the framework of quantum vortex reconnections, where pseudospectral Fourier methods are commonly used and local high resolution is required in the post-processing stage. We show that the efficient evaluation of a truncated Fourier series at arbitrary points provides excellent results at a computational cost much smaller than carrying out a numerical simulation of the problem on a sufficiently fine regular grid that can reproduce comparable details of the reconnecting vortices

The Leja method revisited: backward error analysis for the matrix exponential

The Leja method is a polynomial interpolation procedure that can be used to compute matrix functions. In particular, computing the action of the matrix exponential on a given vector is a typical application. This quantity is required, e.g., in exponential integrators. The Leja method essentially depends on three parameters: the scaling parameter, the location of the interpolation points, and the degree of interpolation. We present here a backward error analysis that allows us to determine these three parameters as a function of the prescribed accuracy. Additional aspects that are required for an efficient and reliable implementation are discussed. Numerical examples that illustrate the performance of our Matlab code are included

VALORIZZAZIONE DEI BENI CULTURALI. APPUNTI SU VILLA ADRIANA

Si può definire la “valorizzazione” come l’insieme delle strategie finalizzate all’individuazione e raggiungimento del punto di incontro tra una domanda di sapere e comfort (espressa dal pubblico) e un’offerta di ostensione e servizi (prodotta a una istituzione pubblica o privata), dove la “promozione” agisce come stimolatore della prima e l’impiego di “risorse”, come organizzatore e pianificatore della seconda

DE PROSPECTIVA MUNIENDI

La vicenda realizzativa di Via dei Fori Imperiali è radicata nella pianificazione urbanistica di Roma Capitale a partire dal Piano Regolatore del 1873, nel quale veniva per la prima volta ipotizzato un tracciato che, in due tronconi spezzati in prossimità dell'attuale Largo Corrado Ricci, collegava Piazza Venezia con il Colosseo. L'ipotesi di questo collegamento è rimasta in tutta la pianificazione successiva entrando, nel 1911, a sistema con il progetto di liberazione del Foro di Augusto e del Foro di Traiano messo a punto da Corrado Ricci, e assunto nel 1924 dal vigente Piano Regolatore SanjustThe completion of Via dei Fori Imperiali has been rooted in Roma Capitale's urban planning since the Development Plan of 1873, wherein it was theorised for the first time that a path, in two split sections close to the current Largo Corrado Ricci, would link Piazza Venezia with the Colosseum. The idea of this connection remained in all subsequent planning and entering, in 1911, into the scheme with the liberation project of Forum of Augustus and Trajan's Forum developed by Corrado Ricci, and adopted in 1924 to the applicable Sanjust Development Plan

UN FORUM SERIES – are infrastructure investors exempt from human rights duties? G20 surely thinks so…

This post was contributed by Aldo Caliari, Director of the Rethinking Bretton Woods Project at the Washington DC-based Center of Concern. With this year’s United Nations (UN) Business and Human Rights Forum (November 16-18) scheduled to take place at almost the same time as the Group of 20 Summit (November 14-15), the temptation to highlight the dissonance between what is happening in each of these venues is just too great to resist

Accurate evaluation of divided differences for polynomial interpolation of exponential propagators

In this paper, we propose an approach to the computation of more accurate divided differences for the interpolation in the Newton form of the matrix exponential propagator phi(hA) v, phi(z) = (e(z)-1)/z. In this way, it is possible to approximate.( hA) v with larger time step size h than with traditionally computed divided differences, as confirmed by numerical examples. The technique can be also extended to "higher" order phi(k) functions, k >= 0

High voltage covered conductor overhead lines: detection of incipient tree faults

The aim of this thesis is the study of a new type of high voltage overhead power line, made by means of an insulation layer located around the conductor: these are the covered conductor lines. In particular, the work focuses on the study of the behaviour of these conductors when they get in contact with the vegetation around, which can touch or fall on the line.ope

Rastreamento de discromatopsia em estudantes do ensino básico de uma escola da redee pública municipal de Florianópolis.

Trabalho de Conclusão de Curso - Universidade Federal de Santa Catarina. Curso de Medicina. Dapartamento de Clínica Cirúrgica