Search results for "on-line"
showing 10 items of 206 documents
Conversion electron spectroscopy at IGISOL
2012
Conversion elecron spectroscopy has been an important part of the nuclear spectrocopy research at the Department of Physics of the University of Jyv¨askyl¨a since the commissioning of the first cyclotron in the mid 1970s. At the IGISOL facility a specialiced conversion electron spectrometer ELLI was developed in the late 1980s. The first results with ELLI were obtained using the beams from the old MC-20 cyclotron to study newly discovered isotopes of refractory fission products. In the present K130 cyclotron laboratory ELLI has been utilized in many decay-spectroscopy experiments both neutron-deficient and neutron-rich side of the valley of stability. In the early 2000s the new JYFLTRAP ion…
Calibration of advanced Virgo and reconstruction of the gravitational wave signal h(t) during the observing run O2
2018
In August 2017, Advanced Virgo joined Advanced LIGO for the end of the O2 run, leading to the first gravitational waves detections with the three-detector network. This paper describes the Advanced Virgo calibration and the gravitational wave strain h(t) reconstruction during O2. The methods are the same as the ones developed for the initial Virgo detector and have already been described in previous publications, this paper summarizes the differences and emphasis is put on estimating systematic uncertainties. Three versions of the h(t) signal have been computed for the Virgo O2 run, an online version and two post-run reprocessed versions with improved detector calibration and reconstruction…
Numerical study of an optical regenerator exploiting self-phase modulation and spectral offset filtering at 40 Gbit/s
2008
Topic: Nonlinear optics; International audience; In this work, we numerically investigate the performances of optical regenerators based on self-phase modulation and spectral offset filtering at 40 Gbit/s. We outline the different effects affecting the device performances and explain the choice of the optimal working power. The impact of the regenerator on the output signal is also analysed through a statistical approach. Both single- and double-stage configurations are investigated.
Le perquisizioni on-line: un fenomeno sfuggente e in continua evoluzione
2018
Il fenomeno delle perquisizioni on-line - che consente, ai fini investigativi, la raccolta di una grande varietà di dati - è difficilmente inquadrabile e non risulta attualmente disciplinato dal nostro ordinamento. Un'analisi comparatistica e uno sguardo alle fonti sovranazionali permettono di affrontare più compiutamente la tematica, di particolare attualità, evidenziandone i principali aspetti critici.
Multiple four-wave mixing in optical fibers: 1.5–3.4-THz femtosecond pulse sources and real-time monitoring of a 20-GHz picosecond source
2010
International audience; In this work, we report recent progress on the design of all-fibered ultra-high repetition-rate pulse sources for telecommunication applications around 1550 nm. The sources are based on the non-linear compression of an initial beat-signal through a multiple four-wave mixing process taking place into an optical fiber. We experimentally demonstrate real-time monitoring of a 20 GHz pulse source having an integrated phase noise 0.01 radian by phase locking the initial beat note against a reference RF oscillator. Based on this technique, we also experimentally demonstrate a well-separated high-quality 110 fs pulse source having a repetition rate of 2 THz. Finally, we show…
Multiperiodic pulsations in the Be stars NW Serpentis and V1446 Aquilae
2007
Aims.We present accurate photometric time series of two Be stars: NW Ser and V1446 Aql . Both stars were observed at the Observatorio de Sierra Nevada (Granada) in July 2003 with an automatic four-channel Strömgren photometer. We also present a preliminary theoretical study showing that the periodic variations exhibited by these stars can be due to pulsation. Methods.An exhaustive Fourier analysis together with a least-square fitting has been carried out on the time series for all four Strömgren bands. Several independent frequencies and non-periodic trends explain most of the variance. A theoretical non-adiabatic code applied to stellar models for these stars shows that g-modes are unstabl…
Modeling spectral correlations of photon-pairs generated in liquid-filled photonic crystal fiber
2020
The generation of photon-pairs with controllable spectral correlations is crucial in quantum photonics. Here we present the design of a photonic crystal fiber to generate widely-spaced four-wave mixing bands with spectral correlations that can be tuned through the thermo-optic effect after being infiltrated with heavy water. We present a theoretical study of the purity of the signal (idler) photon generated as a function of temperature, pump spectral linewidth and the length of the fiber. 511-6/18-8876 CIIC155/2019 APN-624 TEC2016- 76664-C2-1-R PROMETEO/2019/048
Approach to rotor-shaft hysteretic whirl using Krylov-Bogoliubov techniques
2013
The internal friction associated with the shaft hysteresis or with the possible release of some shrink-fit coupling exerts a destabilizing effect on the over-critical rotor running, but may be efficiently counteracted by other external dissipative sources or by a proper anisotropic configuration of the support stiffness. The present analysis considers a symmetric rotor-shaft system on viscous-flexible supports with different stiffness on two orthogonal planes containing the bearing axis. The internal friction of the shaft is described either by a linear hysteretic model or by a nonlinear Coulombian force contrasting the rotor motion relative to the shaft ends. The nonlinear equations of mo…
Finite difference time domain simulation of soil ionization in grounding systems under lightning surge conditions
2004
This paper proposes a Maxwell’s equations finite difference time domain (FDTD) approach for electromagnetic transients in ground electrodes in order to take into account the non linear effects due to soil ionization. A time variable soil resistivity method is used in order to simulate the soil breakdown, without the formulation of an initial hypothesis about the geometrical shape of the ionized zone around the electrodes. The model has been validated by comparing the computed results with available data found in technical literature referred to concentrated earths. Some application examples referred to complex grounding systems are reported to show the computational capability of the propos…
A finite difference time domain model for the Titan ionosphere Schumann resonances
2007
[1] This paper presents a numerical approach to model the electrical properties of Titan's atmosphere. The finite difference time domain technique is applied to model the atmosphere of Saturn's satellite in order to determine Schumann resonant frequencies and electromagnetic field distributions at the extremely low frequency range. Spherical coordinates are employed, and periodic boundary conditions are implemented in order to exploit the symmetry in rotation of the celestial body. Results are compared with a previous model using the transmission line matrix method up to 180 km altitude. For the first time a numerical FDTD model up to 800 km altitude is carried out, and we report lower freq…