Search results for "armo"
showing 10 items of 1364 documents
Microwave harmonic emission in MgB2 superconductor: Comparison with YBA2CU3O7
2006
We report results of microwave second-harmonic generation in ceramic samples of MgB2, prepared by different methods. The SH signal has been investigated as a function of the temperature and the static magnetic field. The results are discussed in the framework of models reported in the literature. We show that the peculiarities of the SH signal are related to the specific properties of the sample. A comparison with the results obtained in ceramic and crystalline YBa2Cu3O7 shows that the second-harmonic emission in MgB2 is weaker than that observed in ceramic YBa2CuO7. (c) 2006 Wiley Periodicals, Inc.
High efficiency frequency doubling in fully diced LiNbO3ridge waveguides on silicon
2016
Nonlinear periodically poled ridge LiNbO3 waveguides have been fabricated on silicon substrates. Components are carved with only the use of a precision dicing machine without the need for grinding or polishing steps. They show efficient second harmonic generation at telecommunication wavelengths with normalized conversion reaching 204%/W in a 15 mm long device. The influence of the geometrical non uniformities of waveguides due to fabrication processes is asserted. Characteristics of the components are studied; notably their robustness and tunability versus temperature.
Hierarchical fast BEM for anisotropic time-harmonic 3-D elastodynamics
2012
The paper presents a fast boundary element method for anisotropic time-harmonic 3-D elastodynamic problems. The approach uses the hierarchical matrices format and the ACA algorithm for the collocation matrix setup and a preconditioned GMRES solver for the solution. The development of this approach for the anisotropic case presents peculiar aspects which deserve investigation and are studied in the paper leading to the employed computational strategy and its effective tuning. Numerical experiments are presented to assess the method accuracy, performances and numerical complexity. The method ensures adequate accuracy allowing remarkable reductions in computation time and memory storage.
Doni funesti. Miti di scambi pericolosi nella letteratura latina
2018
«I doni sono come gli ami» avverte Marziale. «Catturano anche gli dèi» afferma Ovidio. «Sono l’inganno in cui di solito incappano i re» osserva Seneca. La forza calamitante del dono, la sua natura seducente e pericolosa, emerge con chiarezza dall’analisi del sapere mitico romano e delle sue riscritture letterarie. I Romani, del resto, conoscevano bene il potere attrattivo dei doni, la loro capacità di condizionare i comportamenti e le dinamiche di relazione. Erifile è soggiogata dalla collana di Armonia, Mida è accecato dalla sua fame d’oro, Creusa è ingannata dai doni nuziali; Didone brucia con sé quelli dell’amato, Semele e Fetonte ne saranno bruciati. Il dono promesso è un rischio, il do…
Towards CEP stable, single-cycle pulse compression with bulk material
2010
We demonstrate both experimentally and numerically that self-steepening during propagation in a hollow-fiber followed by linear propagation through glass in the anomalous dispersion enables pulse compression down to 1.6 cycles at 1.8 µm wavelength.
Experimental properties of parabolic pulses generated via Raman amplification in standard optical fibers
2004
Parabolic pulses at 1550 nm have been generated in a standard telecommunications fiber using Raman amplification. The parabolic output pulse characteristics are studied as a function of input pulse energy and duration.
Generazione di Seconda Armonica per Quasi-Phase-Matching Random in Tantalato di Litio con Poling Periodico
2009
We experimentally observed and explained bulk Second Harmonic Generation via Random Quasi-Phase-Matching, derived from a periodically poled Lithium Tantalate sample with a randomly patterned mark-to-space-ratio.
Horseshoe-shaped maps in chaotic dynamics of long Josephson junction driven by biharmonic signals
2000
Abstract A collective coordinate approach is applied to study chaotic responses induced by an applied biharmonic driven signal on the long Josephson junction influenced by a constant dc-driven field with breather initial conditions. We derive a nonlinear equation for the collective variable of the breather and a new version of the Melnikov method is then used to demonstrate the existence of Smale horseshoe-shaped maps in its dynamics. Additionally, numerical simulations show that the theoretical predictions are well reproduced. The subharmonic Melnikov theory is applied to study the resonant breathers. Results obtained using this approach are in good agreement with numerical simulations of …
Diffusive energy growth in classical and quantum driven oscillators
1991
We study the long-time stability of oscillators driven by time-dependent forces originating from dynamical systems with varying degrees of randomness. The asymptotic energy growth is related to ergodic properties of the dynamical system: when the autocorrelation of the force decays sufficiently fast one typically obtains linear diffusive growth of the energy. For a system with good mixing properties we obtain a stronger result in the form of a central limit theorem. If the autocorrelation decays slowly or does not decay, the behavior can depend on subtle properties of the particular model. We study this dependence in detail for a family of quasiperiodic forces. The solution involves the ana…
Numerical investigation of optical heartbeats with external driving forces
2010
The role of harmonic and random external forces in a phenomenological nonlinear model of optical heartbeats is investigated. External forces trigger damped oscillations at the natural frequency of the system and higher harmonics. The numerical results are compared with experimental ones.