Spacetime metric from linear electrodynamics

The Maxwell equations are formulated on an arbitrary (1+3)-dimensional manifold. Then, imposing a (constrained) linear constitutive relation between electromagnetic field $(E,B)$ and excitation $({\cal D},{\cal H})$, we derive the metric of spacetime therefrom.Comment: 4 pages' latex-scrip

Naturwall: active timber wall for renovation of existent buildings

The renovation of old buildings is actually the challenge to cope with increased effort in order to reduce climate global change, channeling more investment and awareness in this sense, defining more experimentations and find innovative solutions. The difficulty of carrying out an intervention on the existing buildings necessarily arise from the lack of information on the existing structure and the lack of coordinated processes between the multidisciplinary skills involved, as well as a difficulty to optimize the process that would make it even more competitive on the renovation work instead on the new construction. Naturwall is an innovative energy saving system for existent buildings by using wood in multifunctional components able to mitigate the environmental effort in building management. The project meant to introduce an industrialized design method in the renovation of existing build environment that highlights opportunities gave by "off site" production and parametric design approach, without neglecting the aesthetical values and the possibility to change the architectural image of residential and non residential constructions. The project aims to create a representative model of solution that will be promoted in Italy and widespread in other similar contex

Pairing of 1D Bose-Fermi mixtures with unequal masses

We have considered one-dimensional Bose-Fermi mixture with equal densities and unequal masses using numerical density matrix renormalization group (DMRG). For the mass ratio of K-Rb mixture and attraction between bosons and fermions, we determined the phase diagram. For weak boson-boson interactions, there is a direct transition between two-component Luttinger liquid and collapsed phases as the boson-fermion attraction is increased. For strong enough boson-boson interactions, we find an intermediate "paired" phase, which is a single-component Luttinger liquid of composite particles. We investigated correlation functions of such a "paired" phase, studied the stability of "paired" phase to density imbalance, and discussed various experimental techniques which can be used to detect it.Comment: 7 pages, 5 figure

The fitting of multifunctions : an approach to nonparametric multimodal regression.

In the last decades a lot of research has been devoted to smoothing in the sense of nonparametric regression. However, this work has nearly exclusively concentrated on fitting regression functions. When the conditional distribution of y|x is multimodal, the assumption of a functional relationship y = m(x) + noise might be too restrictive. We introduce a nonparametric approach to fit multifunctions, allowing to assign a set of output values to a given x. The concept is based on conditional mean shift, which is an easily implemented tool to detect the local maxima of a conditional density function. The methodology is illustrated by environmental data examples

Density Matrix Renormalization Group for Dummies

We describe the Density Matrix Renormalization Group algorithms for time dependent and time independent Hamiltonians. This paper is a brief but comprehensive introduction to the subject for anyone willing to enter in the field or write the program source code from scratch.Comment: 29 pages, 9 figures. Published version. An open source version of the code can be found at http://qti.sns.it/dmrg/phome.htm

Space geometry of rotating platforms: an operational approach

We study the space geometry of a rotating disk both from a theoretical and operational approach, in particular we give a precise definition of the space of the disk, which is not clearly defined in the literature. To this end we define an extended 3-space, which we call relative space: it is recognized as the only space having an actual physical meaning from an operational point of view, and it is identified as the 'physical space of the rotating platform'. Then, the geometry of the space of the disk turns out to be non Euclidean, according to the early Einstein's intuition; in particular the Born metric is recovered, in a clear and self consistent context. Furthermore, the relativistic kinematics reveals to be self consistent, and able to solve the Ehrenfest's paradox without any need of dynamical considerations or ad hoc assumptions

Auralization of Amplitude Modulated Helicopter Flyover Noise

Rotorcraft noise is an active field of study as the sound produced by these vehicles is often found to be annoying. A means to auralize rotorcraft flyover noise is sought to help understand the factors leading to annoyance. Previous work by the authors auralized a complete flyover event in which the source noise synthesis traversed a range of emission angles. The source noise definition process for the synthesis used helicopter flyover recordings. Although this process yielded both periodic and aperiodic (modulation) components at a set of discrete emission angles, only the periodic components were used in the previous work to synthesize the sound of the flyover event. In the current work, aperiodic amplitude modulation is incorporated into the source noise synthesis to improve its fidelity toward assessing rotorcraft noise annoyance. The method is demonstrated using ground recordings from a flight test of the AS350 helicopter for the source noise definition

HIGH TEMPERATURE OXIDATION PHENOMENA'S STUDY OF HIGH ALLOYED MATERIALS FOR POWER GENERATION PLANTS

The aim of the doctorate project is the study of the corrosion and oxidation behavior of some commercial and more recent SS and Ni based alloys for high temperature applications in order to verify their possible use either at operative conditions higher than conventional (temperature up to 900\ub0C) or in different environment (oxygen, air, carburizing atmospheres). During the first year, the following aspects were investigated: - Microstructural characterization of solution annealed AISI 310N, 347HFG and 304 HCu (the latter supplied also in the shoot peened condition) was carried out. An homogeneous austenitic fine grain structure accompanied with Nb segregation was observed for 347HFG and 304HCu. In the case of 310N the grains were coarser and the presence of Si segregation were randomly detected beside Nb. - Microhardness profiles (HV50) were conducted to evaluate the penetration effects of shoot peening treatment at depths as high as 150-200 \uf06dm. - Discontinuous oxidation testing were performed at temperatures in the range of 700-900\ub0C under 15 Nm3/h flowing moist air atmosphere for 7 days. The preliminary results seem to confirm an oxidation susceptibility in the following order: 310N<347HFG<304HCu. During the second year, the following activities have been carried out: - Oxidation kinetic study (thermogravimetric tests) of as received AISI 310N, 347HFG, 304HCu and Alloy 617 in oxygen atmosphere at 900\ub0C; 310N, 347HFG and Alloy 617 show a protective oxidation kinetic, while 304HCu suffers from spalling. - Investigation of grown oxide layer nature of all SS by microscopic techniques revealed an average oxide thickness in the range of 5 \u2013 15 \uf06dm for 347HFG; about 5 \uf06dm until spallation for 304HCu and less than 5 \uf06dm for 310N. In the case of 347HFG a three layer oxide was clearly detected consisting of a first layer of Cr oxides followed by a mixed Fe and Cr oxide and finally an external layer of FeOx. For 310N only a Cr oxide layer was detectable; for 304HCu the layer being essentially Fe-Cr oxides. Result confirmed also by GDOES. - Study of the electrochemical behaviour of as received and oxidized SS specimens by means of polarization curves. All \u201cas received\u201d specimens exhibit a similar passive behaviour in terms of both potentials and current densities, apart the point corresponding at the critical passive current (icr). For oxidized specimens a statistical approach should be followed. During the third year, in addition to the accomplishment of the previous topics, new electrochemical approaches were tested during a period spent by the candidate following Dr. Digby Macdonald's research labs at The Pennsylvania State University. Activities were focused on the passivity study of 347HFG stainless steel. Starting from the results of the potentiodynamic studies, an electrochemical impedance spectroscopy procedure was setted up; results were optimized by applying the \u201cpoint defect model\u201d developed by the same Dr. Macdonald revealing kinetic parameters of the passive layer and is semiconductive nature that is essentially n-type for all anodic potential values except near the breakdown in which assume a p-type character

Identifying DsJ(2700)D_{sJ}(2700) through its decay modes

We study how to assign the recently observed $D_{sJ}(2700)$ meson to an appropriate level of the $c \bar s$ spectrum by the analysis of its decay modes in final states comprising a light pseudoscalar meson. We use an effective lagrangian approach with heavy quark and chiral symmetries, obtaining that the measurement of the $D^* K$ decay width would allow to distinguish between two possible assignments.Comment: RevTex, 6 pages - references adde