Polytechnic University of Turin

About: Polytechnic University of Turin is a education organization based out in Turin, Piemonte, Italy. It is known for research contribution in the topics: Finite element method & Computer science. The organization has 11553 authors who have published 41395 publications receiving 789320 citations. The organization is also known as: POLITO & Politecnico di Torino.

Vibration energy scavenging via piezoelectric bimorphs of optimized shapes

Abstract: Compact autonomous power sources are one of the prerequisites for the development of wireless sensor networks. In this work vibration energy harvesting via piezoelectric resonant bimorph beams is studied. The available analytical approaches for the modeling of the coupled electromechanical behavior are critically evaluated and compared with a finite element (FEM) numerical model. The latter is applied to analyze thoroughly the stress and strain states, as well as to evaluate the resulting voltage and charge distributions in the piezoelectric layers. The aim of increasing the specific power generated per unit of scavenger volume is pursued by optimizing the shape of the scavengers. Two optimized trapezoidal configurations are hence identified and analyzed. An experimental set-up for the validation of the proposed numerical model and of the obtained optimized structures is developed. Results of a preliminary experimental assessment, confirming the improved performances of optimized scavengers, are finally given.

A note on the derivation and use of reduced-order models

Abstract: In view of the particular interest in the problem of reduced-order modeling in recent years, some considerations not sufficiently investigated in current literature are pointed out and a comprehensive set of references is given.

High-Level Modulation and Coding for Nonlinear Satellite Channels

Abstract: Currently, 4-PSK is the prevalent modulation format in use for digital satellite communications. To improve bandwidth efficiency, 8PSK could be used instead, but a higher power would be needed; to improve power efficiency, error-correcting codes could be used, but at the expense of a larger bandwidth. Recently, Ungerboeck [1] has proposed a class of codes in which a constellation of 2M signals is used to transmit information at the rate of log_{2} M bits per symbol, and has shown that coding gains of up to several decibels can be achieved on the additive white Gaussian noise (AWGN) channel with no increase in bandwidth occupancy and a relatively small added complexity. Thus, these codes seem to be particularly attractive for application in the band-limited environment typical of satellite communication systems, provided that the performance gain that they provide on the AWGN channel is not lost over a satellite channel. The goal of this work is to assess the performance of this class of codes when used to transmit 3 information bits per symbol on a band-limited, nonlinear satellite channel. Three modulation formats are considered, namely 16-PSK, 16-QAM, and a 16-ary amplitude-phase keying scheme with two amplitude levels. It is found that 16-PSK outperforms the two other modulation formats, and that the use of these codes can provide a substantial performance improvement even on a satellite channel.