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Nonlinear Tuned Mass Damper for self-excited oscillations
Gattulli, Vincenzo,Di Fabio, Franco,Luongo, Angelo Techno-Press 2004 Wind and Structures, An International Journal (WAS Vol.7 No.4
The effects of a class of nonlinear Tuned Mass Dampers on the aeroelastic behavior of SDOF systems are investigated. Unlike classical linear TMDs, nonlinear constitutive laws of the internal damping acting between the primary oscillator and the TMD are considered, while the elastic properties are keept linear. The perturbative Multiple Scale Method is applied to derive a set of bifurcation equations in the amplitude and phase and a parametric analysis is performed to describe the postcritical scenario of the system. Both cubic- and van der Pol-type dampings are considered and the dependence of the limit-cycle amplitudes on the system parameters is studied. These new results, compared with the previously obtained bifurcation scenario of a SDOF aeroelastic oscillator equipped with a linear TMD, show a detrimental effect on the maximum limit-cycle amplitude reduction of the nonlinear TMD. However, the analyses evidence that in the parameter region away from the perfect tuning condition the nonlinear connection can be used to tune the system with an enhancement of the limit-cycle amplitude reduction.
Spera, M.,Corso, D.,Di Franco, S.,Greco, G.,Severino, A.,Fiorenza, P.,Giannazzo, F.,Roccaforte, F. Elsevier 2019 Materials science in semiconductor processing Vol.93 No.-
<P><B>Abstract</B></P> <P>This work reports on the effect of high temperature annealing on the electrical properties of p-type implanted 4H-SiC. Ion implantations of Aluminum (Al) at different energies (30–200 keV) were carried out to achieve 300 nm thick acceptor box profiles with a concentration of about 10<SUP>20</SUP> at/cm<SUP>3</SUP>. The implanted samples were annealed at high temperatures (1675–1825 °C). Morphological analyses of the annealed samples revealed only a slight increase of the surface roughness RMS up to 1775 °C, while this increase becomes more significant at 1825 °C (RMS = 1.2 nm). Room temperature Hall measurements resulted in a hole concentration in the range 0.65–1.34 × 10<SUP>18</SUP>/cm<SUP>3</SUP> and mobility values in the order of 21–27 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>. The temperature dependent electrical measurements allowed to estimate an activation energy of the Al-implanted specie of about 110 meV (for the post-implantation annealing at 1675 °C) and a fraction of active p-type Al-dopant ranging between 39% and 56%. The results give useful indications for the fabrication of 4H-SiC JBS and MOSFETs.</P>
A facile way to synthesize noble metal free TiO2 based catalysts for glycerol photoreforming
Claudio M. Pecoraro,Marianna Bellardita,Vittorio Loddo,Francesco Di Franco,Leonardo Palmisano,Monica Santamaria 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.118 No.-
In this work anaerobic heterogeneous photocatalytic solar/UV light reforming of glycerol in aqueousmedia was performed with Pt-photodeposition and noble metal free modified TiO2 photocatalysts preparedthrough ball milling, a very simple and cheap coupled catalyst preparation method. Differentamounts of Cu2O or 3% CuO were loaded on TiO2 using ball milling and during each run glycerol conversion,hydrogen and CO2 formed in the gas phase and 1,3-dihydroxyacetone (DHA) and glyceraldehyde(GA) in the liquid phase were determined. The results were compared with the aim to verify the effectivenessof Cu2O in replacing Pt. Using noble metal free photocatalysts, 33% glycerol conversion, 10.3%and 5.4% selectivity towards DHA and GA, respectively, a CO2 concentration of 0.16 mM, and a H2 concentrationof 1.01 mM corresponding to 0.17 mmol h1 g1 were obtained. Ex situ photoelectrochemicalcharacterization confirmed the formation of a heterostructure between TiO2 and copper oxide and theeffectiveness of Cu2O towards H2 formation.