624 research outputs found
Simple and Low Cost 10 Gb/s Coherent Transmission for Long Reach PON
131 km transmission (typical LR-PON distance) at 10Gb/s over G.652 fiber is demonstrated
exploiting a direct modulated (DM) DFB laser, coherent receiver and electrical filtering obtaining an
innovative chirp managed approach. No dispersion compensation (optical or DSP) is exploited
Ultra-Dense WDM-PON 6.25 GHz spaced 8x1 Gb/s based on a simplified coherent-detection scheme
We demonstrate experimentally a novel type of coherent low cost Gigabit-to-the-User Ultra-Dense-Wavelength Division Multiplexing (UD-WDM) PON, featuring 6.25 GHz channel spacing and long reach. Polarization-independent coherent detection is achieved by exploiting a novel scheme which requires only a 3×3 coupler, three photodiodes, basic analogue processing and a common DFB as local oscillator (LO). This avoids the conventional polarization diversity approach. The DFB LO is free running, i.e. not locked in frequency, and is tuned to detect any of the eight channels by simply changing its temperature in a range of 2° C. We achieve 70 km long-reach transmission plus 30 dB attenuation, for a total of > 45 dB optical distribution network loss. This indicates that this solution could be effectively exploited to overlay existing PON infrastructures by UD-WDM
PassGAN: A Deep Learning Approach for Password Guessing
State-of-the-art password guessing tools, such as HashCat and John the
Ripper, enable users to check billions of passwords per second against password
hashes. In addition to performing straightforward dictionary attacks, these
tools can expand password dictionaries using password generation rules, such as
concatenation of words (e.g., "password123456") and leet speak (e.g.,
"password" becomes "p4s5w0rd"). Although these rules work well in practice,
expanding them to model further passwords is a laborious task that requires
specialized expertise. To address this issue, in this paper we introduce
PassGAN, a novel approach that replaces human-generated password rules with
theory-grounded machine learning algorithms. Instead of relying on manual
password analysis, PassGAN uses a Generative Adversarial Network (GAN) to
autonomously learn the distribution of real passwords from actual password
leaks, and to generate high-quality password guesses. Our experiments show that
this approach is very promising. When we evaluated PassGAN on two large
password datasets, we were able to surpass rule-based and state-of-the-art
machine learning password guessing tools. However, in contrast with the other
tools, PassGAN achieved this result without any a-priori knowledge on passwords
or common password structures. Additionally, when we combined the output of
PassGAN with the output of HashCat, we were able to match 51%-73% more
passwords than with HashCat alone. This is remarkable, because it shows that
PassGAN can autonomously extract a considerable number of password properties
that current state-of-the art rules do not encode.Comment: This is an extended version of the paper which appeared in NeurIPS
2018 Workshop on Security in Machine Learning (SecML'18), see
https://github.com/secml2018/secml2018.github.io/raw/master/PASSGAN_SECML2018.pd
Investigation of the Effects of Chirped RZ Signals in Reducing the Transmission Impairments in R-SOA-Based Bidirectional PONs
Distributed and concentrated reflections represent
the two main limitations in reflective-semiconductor optical amplifier (R-SOA)-based passive optical networks (PONs). In this
paper, we experimentally discuss how the use of chirped signals
in centralized light seeding bidirectional PON can increase the
resilience of the system against those two types of reflections. An
experimental comparison of the performance of a highly chirped
return to zero (RZ) modulation format and the nonreturn to zero
is given. Error-free operation is achieved down to 10 dB of signal
to crosstalk ratio in presence of distributed reflection, when the
upstream signal is highly chirped RZ signal. The same chirped
modulation leads to a tolerance of more than dB network
return loss due to concentrated reflections. Finally, we assess also
the system feasibility of a R-SOA-based full-duplex PON where
both the upstream and the downstream are modulated signals
Promotion of Resilience in Migrants: A Systematic Review of Study and Psychosocial Intervention
This systematic review aimed to contribute to a better and more focused understanding of the link between the concept of resilience and psychosocial interventions in the migrant population. The research questions concerned the type of population involved, definition of resilience, methodological choices and which intervention programmes were targeted at migrants. In the 90 articles included, an heterogeneity in defining resilience or not well specified definition resulted. Different migratory experiences were not adequately considered in the selection of participants. Few resilience interventions on migrants were resulted. A lack of procedure’s descriptions that keep in account specific migrants’ life-experiences and efficacy’s measures were highlighted
System feasibility of using stimulated Brillouin scattering in self coherent detection schemes
We demonstrate the first self-coherent detection of 10 Gbit/s BPSK signals based on narrow-band amplification of the optical carrier by means of Stimulated Brillouin effect in a common fiber. We found that this technique is very effective only if it is combined with proper line coding and high-pass electrical filtering at the receiver. In this case we obtain OSNR-performance close to the ideal coherent receiver. (C) 2010 Optical Society of Americ
Optimal design of experiments for a lithium-ion cell: parameters identification of an isothermal single particle model with electrolyte dynamics
Advanced battery management systems rely on mathematical models to guarantee
optimal functioning of Lithium-ion batteries. The Pseudo-Two Dimensional (P2D)
model is a very detailed electrochemical model suitable for simulations. On the
other side, its complexity prevents its usage in control and state estimation.
Therefore, it is more appropriate the use of simplified electrochemical models
such as the Single Particle Model with electrolyte dynamics (SPMe), which
exhibits good adherence to real data when suitably calibrated. This work
focuses on a Fisher-based optimal experimental design for identifying the SPMe
parameters. The proposed approach relies on a nonlinear optimization to
minimize the covariance parameters matrix. At first, the parameters are
estimated by considering the SPMe as the real plant. Subsequently, a more
realistic scenario is considered where the P2D model is used to reproduce a
real battery behavior. Results show the effectiveness of the optimal
experimental design when compared to standard strategies.Comment: Published in Ind. Eng. Chem. Res. 2019, 58, 3, 1286-129
Hybrid Radio over Fiber and Visible Light (RoF-VLC)Communication System
We experimentally demonstrate the integration of Radio-over-Fiber and Visible Light
Communication technologies, into a hybrid system for indoor communication. The system,
realized according to IEEE 802.11g standard, works effectively at typical office luminance level
A simple and low-power optical limiter for multi-GHz pulse trains
We study the limiting-amplification capability of a saturated Semiconductor Optical Amplifier (SOA) followed by an optical band-pass filter. We experimentally demonstrate that this simple optical circuit can be effectively exploited to realize a low-power optical limiter for amplitude-modulated pulse trains at multi-GHz repetition rate. We report very large amplitude-modulation-reduction factors for the case of 20 and 40 GHz pulse trains that are super-imposed with modulating frequencies ranging from 100kHz to several GHz. (C) 2007 Optical Society of America
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