Recurrence plots of sunspots, solar flux and irradiance

The paper shows the recurrence and cross recurrence plots of three time series, concerning data of the solar activity. The data are the sunspot number and the values of solar radio flux at 10.7 cm and of solar total irradiance, which are known as highly correlated. To compare the series, the radio flux and irradiance values are monthly averaged. Recurrence plots display the oscillating behaviour with remarkable features. Moreover, cross recurrence plots help in identifying time lags between the sunspot number maximum and the maximum of radio or irradiance signals, in circumstances where the data values are highly dispersed. Image processing is useful too, in enhancing the monitoring. An interesting behaviour is displayed by cross recurrence plots of irradiance, which are not symmetric with respect to the line of identity

Digital Restoration of Ancient Papyri

Image processing can be used for digital restoration of ancient papyri, that is, for a restoration performed on their digital images. The digital manipulation allows reducing the background signals and enhancing the readability of texts. In the case of very old and damaged documents, this is fundamental for identification of the patterns of letters. Some examples of restoration, obtained with an image processing which uses edges detection and Fourier filtering, are shown. One of them concerns 7Q5 fragment of the Dead Sea Scrolls

Synchronization of Kuramoto Oscillators on Knots

A knot is a circle embedded in the space. Projecting a knot on a plane, we obtain a diagram which is known as the knot diagram. The vertices of the diagram, where the curved lines are crossed, can be considered as sites occupied by oscillators. The synchronization of these oscillators can be studied by means of a Kuramoto model. Here we propose to define some order parameters, of the complete knot diagram and of its regions, to study the synchronization of the system with regard to the different parts of it.Comment: Knots, Knot diagrams, Kuramoto model, (revised title

Jerk and Hyperjerk in a Rotating Frame of Reference

Jerk is the derivative of acceleration with respect to time and then it is the third order derivative of the position vector. Hyperjerks are the n-th order derivatives with n>3. This paper describes the relations, for jerks and hyperjerks, between the quantities measured in an inertial frame of reference and those observed in a rotating frame. These relations can be interesting for teaching purposes.Comment: Rotating frames, Physics education researc

Discussion of the De Generatione Sonorum, a treatise on sound and phonetics by Robert Grosseteste

Here I am proposing a translation and discussion of the De Generatione Sonorum, one of the short scientific treatises written by Robert Grosseteste. The subject is the sound and the phonetics. In this treatise we find a discussion of oscillations and elasticity of materials and the description of some motions and their combinations to

Phase Changes Materials and Controls in Thermodynamic Models

Congresso AICA 2011, Torino, 15-17 Novembr