Search results for " Circuits"

Control of signal coherence in parametric frequency mixing with incoherent pumps: Narrowband mid-infrared light generation by downconversion of broad…

2012

International audience; We study, with numerical simulations using the generalized nonlinear envelope equation, the processes of optical parametric and difference- and sum-frequency generation (SFG) with incoherent pumps in optical media with both quadratic and third-order nonlinearity, such as periodically poled lithium niobate. With ultrabroadband amplified spontaneous emission pumps or continua (spectral widths > 10 THz), group-velocity matching of a near-IR pump and a short-wavelength mid-IR (MIR) idler in optical parametric generation may lead to more than 15-fold relative spectral narrowing of the generated MIR signal. Moreover, the SFG process may also lead to 6-fold signal coherence…

A Hardware and Secure Pseudorandom Generator for Constrained Devices

2018

Hardware security for an Internet of Things or cyber physical system drives the need for ubiquitous cryptography to different sensing infrastructures in these fields. In particular, generating strong cryptographic keys on such resource-constrained device depends on a lightweight and cryptographically secure random number generator. In this research work, we have introduced a new hardware chaos-based pseudorandom number generator, which is mainly based on the deletion of an Hamilton cycle within the $N$ -cube (or on the vectorial negation), plus one single permutation. We have rigorously proven the chaotic behavior and cryptographically secure property of the whole proposal: the mid-term eff…

Influence of Active Device Nonlinearities on the Determination of Adler's Injection.Locking Q-Factor

2011

The problem of the correct evaluation of Q-factor appearing in Adler's equation for injection-locking is addressed. Investigation has shown that recent results presented in the literature, while extending applicability of the original method, do not completely account for nonlinear effects occurring when two-port active devices are involved. To overcome such limitation, use can be made of a newly developed theory in the dynamical complex envelope domain, capable of providing first-approximation exact dynamical models of driven quasi-sinusoidal oscillators. Some preliminary results are presented here concerning a class of injection-locked oscillators with single-loop feedback type configurat…

Clustering Quality and Topology Preservation in Fast Learning SOMs

2008

The Self-Organizing Map (SOM) is a popular unsupervised neural network able to provide effective clustering and data visualization for data represented in multidimensional input spaces. In this paper, we describe Fast Learning SOM (FLSOM) which adopts a learning algorithm that improves the performance of the standard SOM with respect to the convergence time in the training phase. We show that FLSOM also improves the quality of the map by providing better clustering quality and topology preservation of multidimensional input data. Several tests have been carried out on different multidimensional datasets, which demonstrate better performances of the algorithm in comparison with the original …

Sentinel-3/FLEX Biophysical Product Confidence Using Sentinel-2 Land-Cover Spatial Distributions

2021

The estimation of biophysical variables from remote sensing data raises important challenges in terms of the acquisition technology and its limitations. In this way, some vegetation parameters, such as chlorophyll fluorescence, require sensors with a high spectral resolution that constrains the spatial resolution while significantly increasing the subpixel land-cover heterogeneity. Precisely, this spatial variability often makes that rather different canopy structures are aggregated together, which eventually generates important deviations in the corresponding parameter quantification. In the context of the Copernicus program (and other related Earth Explorer missions), this article propose…

Bidirectional High-Efficiency Nonisolated Step-Up Battery Regulator

2011

The design and results of a high-efficiency high-power (5 kW) nonisolated bidirectional dc-dc converter is presented. High stability due to minimum phase behavior is an additional benefit of the topology. The converter is a new boost with output filter where input and output inductors are coupled. This converter is useful with any system that needs to charge and discharge backup batteries and can be applied in space, automotive, and telecom power systems.

A new efficiency low mass bi-directional battery discharge-charge regulator for low voltage batteries

2002

Since the policies of the space agencies are focused on the development of smaller satellites, it is becoming more and more important the save of volume and mass in the necessary satellite equipment. Due to this need, the authors introduce a bi-directional battery discharge-charge regulator for low voltage batteries that reaches these new goals and besides which has high efficiency.

E-bike battery charging: Methods and circuits

2013

Today, academic and industrial research is focused on innovative battery charging methods to ensure complete mobility of both handheld devices and electric vehicles. Wireless power transfer is actually the leading strategy even if efficiency related issues are to be solved for a successful marketing. In this paper, a wireless battery charging station is proposed for electric assisted pedal bikes. If compared with existing wireless solutions, the proposed system architecture improves power conversion efficiency of the charging equipment. The simulation model of the whole charging station is described in detail. The transmitter, receiver and inductive coupling circuits are described and desig…

VALUTAZIONE DELLA FATTIBILITA', ACCETTABILITA', COMPRENSIBILITA' E ATTRATTIVITA', DELLA VERSIONE ITALIANA DEL "COMPUTERISED INTERACTIVE REMEDIATION O…

Background: le persone con schizofrenia hanno difficoltà cognitive e nel funzionamento sociale. La Cognitive Remediation Theraphy (CRT) è una terapia psicologica mirata a ridurre tali deficit. CIRCuiTS è una versione computerizzata di CRT, che promuove l'uso di strategie e della metacognizione. CIRCuiTS è risultato efficace e accettabile nei suoi studi originali condotti nel Regno Unito. Obiettivi: valutare la fattibilità, l'accettabilità, la comprensibilità e l'attrattiva della versione italiana di CIRCuiTS per le persone con psicosi. Metodi: sono stati condotti tre studi per valutare la versione italiana di CIRCuiTS. Studio 1, sono state valutate l'aderenza e la soddisfazione in 20 sogget…

Charting the Drosophila neuropile: a strategy for the standardised characterisation of genetically amenable neurites

2003

Insect neurons are individually identifiable and have been used successfully to study principles of the formation and function of neuronal circuits. In the fruitfly Drosophila, studies on identifiable neurons can be combined with efficient genetic approaches. However, to capitalise on this potential for studies of circuit formation in the CNS of Drosophila embryos or larvae, we need to identify pre- and postsynaptic elements of such circuits and describe the neuropilar territories they occupy. Here, we present a strategy for neurite mapping, using a set of evenly distributed landmarks labelled by commercially available anti-Fasciclin2 antibodies which remain comparatively constant between s…