Search results for "FREQUENCY"
showing 10 items of 2158 documents
Hot electrons and nonlinear optical nanoantennas
2017
The large field enhancement generated at the surface of a resonant plasmonic nanoparticle, or optical antennas, is the key mechanism that eventually led to the development of nonlinear plasmonics [1-2]. While the resonance may boost the nonlinear yield of an adjacent structure or surrounding medium, it was soon realized that optical antennas possess nonlinear coefficients comparable or exceeding those of standard nonlinear optical materials [3]. We discuss here two nonlinear optical processes — incoherent multi-photon luminescence (MPL) and coherent second-harmonic generation (SHG) — emitted from gold rod optical antennas upon local illumination with a tightly focused femtosecond near-infra…
Atomic-resolution imaging of the polar (0001¯) surface of LiNbO3in aqueous solution by frequency modulation atomic force microscopy
2012
S. Rode,1 R. Holscher,2 S. Sanna,2 S. Klassen,1 K. Kobayashi,3 H. Yamada,3 W. G. Schmidt,2 and A. Kuhnle1,* 1Institut fur Physikalische Chemie, Fachbereich Chemie, Johannes Gutenberg-Universitat Mainz, Jakob-Welder-Weg 11, 55099 Mainz, Germany 2Lehrstuhl fur Theoretische Physik, Universitat Paderborn, 33095 Paderborn, Germany 3Department of Electronic Science and Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8510, Japan (Received 31 March 2012; revised manuscript received 12 June 2012; published 29 August 2012)
Innovative modeling of Tuned Liquid Column Damper motion
2015
Abstract In this paper a new model for the liquid motion within a Tuned Liquid Column Damper (TLCD) device is developed, based on the mathematical tool of fractional calculus. Although the increasing use of these devices for structural vibration control, it is shown that existing model does not always lead to accurate prediction of the liquid motion. A better model is then needed for accurate simulation of the behavior of TLCD systems. As regards, it has been demonstrated how correctly including the first linear liquid sloshing mode, through the equivalent mechanical analogy well established in literature, produces numerical results that highly match the corresponding experimental ones. Sin…
Anomalous thermalization of nonlinear wave systems
2010
We report theoretically and experimentally in an optical system a process of anomalous thermalization of one-dimensional nonlinear Hamiltonian waves. It is characterized by an irreversible evolution of the waves towards a specific equilibrium state of a fundamental different nature than the expected thermodynamic equilibrium state. A kinetic approach of the problem reveals that this phenomenon is due to the existence of a local invariant in frequency space. A novel family of equilibrium distributions is discovered, which is found in quantitative agreement with the numerical simulations.
Opto-digital tomographic reconstruction of the Wigner distribution function of complex fields.
2008
An optical-digital method has been developed to obtain the Wigner distribution function of one-dimensional complex fields. In this technique an optical setup is employed to experimentally achieve the Radon-Wigner spectrum of the original signal through intensity measurements. Digital tomographic reconstruction is applied to the experimental spectrum to reconstruct the two-dimensional Wigner distribution function of the input. The validity of our proposal is demonstrated with experimental data, and the results are compared with computer simulations.
Characterization and Error Compensation of a Rogowski Coil in the Presence of Harmonics
2011
This paper reports the results of an experimental study dealing with a commercial Rogowski coil current transducer (RCCT) in the presence of harmonic distortion. The RCCT was observed under two conditions: 1) sinusoidal excitation with frequencies from 50 to 750 Hz and 2) nonsinusoidal excitation using fundamental frequency and one harmonic, with adjustable amplitude and phase shift. The experimental results show only a weak dependence of the harmonic current ratio error and phase displacement on the amplitude and phase shift of the excitation harmonic. The phase displacement is also independent of the conductor position within the Rogowski coil window. An error compensation method, based o…
Harmonic reduction in CHB 13-level inverters by PAM fundamental-frequency strategy
2019
In this paper cascaded H-bridges (CHB) 13-level inverters are considered and a particular pulse amplitude modulation (PAM) strategy is introduced to mitigate or eliminate many harmonic components on the output voltage, in order to obtain low Total Harmonic Distortion (THD) factor. This procedure defines different dc voltage sources and sets of six switching angles, depending on an integer parameter $q$ belonging to the close interval $I=[11, 15]$ . The obtained THD doesn't depend on modulation index $m$ . The control of $m$ is made by changing the dc voltage sources that depend linearly on m, while the switching angles remain constant. An investigation about the role of the $q$ parameter on…
The Ramsey method in high-precision mass spectrometry with Penning traps: Theoretical foundations
2007
Abstract This paper presents in a quantum mechanical framework a theoretical description of the interconversion of the magnetron and modified cyclotron motional modes of ions in a Penning trap due to excitation by external rf-quadrupole fields with a frequency near the true cyclotron frequency. The work aims at a correct description of the resonance line shapes that are observed in connection with more complicated excitation schemes using several excitation pulses, such as Ramsey’s method of separated oscillating fields. Quantum mechanical arguments together with the “rotating wave approximation” suggest a model Hamiltonian that permits a rigorous solution of the corresponding Heisenberg eq…
Full Wave Solution for Intel CPU With a Heat Sink for EMC Investigations
2010
A CPU with a heat sink (e.g. Intel Pentium 4 and Intel Pentium dual core) is a challenging problem for EMC analysis. A Very Large Scale Integrated (VLSI) device was modelled using the Finite Element Method (FEM) frequency domain solver to obtain a 3D full wave solution. The electromagnetic (EM) radiation emitted from these high power microelectronic circuits connected to a heat sink was found to have resonant frequencies around 2.4 GHz and 5 GHz with reflection coefficients less than -19 dB and -8 dB respectively. These resonant frequencies are very close to the operating frequency of both IEEE and Bluetooth wireless communication systems. This paper proposes a new benchmark model based on …
Density-near-zero using the acoustically induced transparency of a Fano acoustic resonator
2016
International audience; We report experimental results of near-zero mass density involving an acoustic metamaterial supporting Fano resonance. For this, we designed and fabricated an acoustic resonator with two closely coupled modes and measured its transmission properties. Our study reveals that the phenomenon of acoustically induced transparency is accompanied by an effect of near-zero density. Indeed, the dynamic effective parameters obtained from experimental data show the presence of a frequency band where the effective mass density is close to zero, with high transmission levels reaching 0.7. Furthermore, we demonstrate that such effective parameters lead to wave guiding in a 90-degre…