Search results for " Feedback"

New fiber laser architecture with transform-limited nonlinear spectral compression

2012

International audience; We numerically demonstrate a new fiber laser architecture supporting spectral compression of negatively chirped pulses in passive normally dispersive fiber. Such a process is beneficial for improving the energy efficiency of the cavity as it prevents narrow spectral filtering from being highly dissipative. The proposed laser design provides an elegant way of generating transform-limited picosecond pulses.

P4‐256: POSITIVE FEEDBACK LOOP OF APC/C‐CDH1‐MEDIATED EXCITOTOXICITY IN ALZHEIMER'S DISEASE

2014

Global linear feedback control for the generalized Lorenz system

2006

Abstract In this paper we show how the chaotic behavior of the Chen system can be controlled via feedback technique. We design both a nonlinear feedback controller and a linear one which globally regulate the closed-loop system states to a given point. We finally show that our approach works also for the whole family of the generalized Lorenz system.

Distance-based relevance feedback using a hybrid interactive genetic algorithm for image retrieval

2011

Content-based image retrieval (CBIR) systems aim to provide a means to find pictures in large repositories without using any other information except the own content of the images, which is usually represented as a feature vector extracted from low-level descriptors. This paper describes a CBIR algorithm which combines relevance feedback, evolutionary computation concepts and distance-based learning in an attempt to reduce the existing gap between the high level semantic content of the images and the information provided by their low-level descriptors. In particular, a framework which is independent from the particular features used is presented. The effect of different crossover strategies…

Improving distance based image retrieval using non-dominated sorting genetic algorithm

2015

Image retrieval is formulated as a multiobjective optimization problem.A multiobjective genetic algorithm is hybridized with distance based search.A parameter balances exploration (genetic search) or exploitation (nearest neighbors).Extensive comparative experimentation illustrate and assess the proposed methodology. Relevance feedback has been adopted as a standard in Content Based Image Retrieval (CBIR). One major difficulty that algorithms have to face is to achieve and adequate balance between the exploitation of already known areas of interest and the exploration of the feature space to find other relevant areas. In this paper, we evaluate different ways to combine two existing relevan…

Applying logistic regression to relevance feedback in image retrieval systems

2007

This paper deals with the problem of image retrieval from large image databases. A particularly interesting problem is the retrieval of all images which are similar to one in the user's mind, taking into account his/her feedback which is expressed as positive or negative preferences for the images that the system progressively shows during the search. Here we present a novel algorithm for the incorporation of user preferences in an image retrieval system based exclusively on the visual content of the image, which is stored as a vector of low-level features. The algorithm considers the probability of an image belonging to the set of those sought by the user, and models the logit of this prob…

Nonlinear beam self-cleaning in a coupled cavity composite laser based on multimode fiber

2017

International audience; We study a coupled cavity laser configuration where a passively Q-switched Nd:YAG microchip laser is combined with an extended cavity, including a doped multimode fiber. For appropriate coupling levels with the extended cavity, we observed that beam self-cleaning was induced in the multimode fiber thanks to nonlinear modal coupling, leading to a quasi-single mode laser output. In the regime of beam self-cleaning, laser pulse duration was reduced from 525 to 225 ps. We also observed a Q-switched mode-locked operation, where spatial self-cleaning was accompanied by far-detuned nonlinear frequency conversion in the active multimode fiber.

Improving the Quality of the Comply or Explain Approach and Introducing Self-Monitoring Through Online Feedbacks

2017

Codes of corporate governance and comply or explain approach are always at the core of the European Union agenda. This paper will deal both with the evolution of codes of corporate governance across Europe, and with the 2014 Recommendation. The idea put forwards is that regulators, at both EU and national level, should mainly improve the environment where the comply or explain approach is applied and introduce a system of self-monitoring through online feedbacks only. Arguably, this proposal might offer Member States a light-touch way to comply with Art. 11 of the 2014 Recommendation laying down that “[i]n order to motivate companies to comply with the relevant corporate governance code or …

Geometry and feedback classification of low-dimensional non-linear control systems

2006

The purpose of this thesis is the study of the local and global differential geometry of fully nonlinear smooth control systems on two-dimensional smooth manifolds. We are particularly interested in the feedback-invariants of such systems. In a first part we will use the Cartan's moving frame method in order to determine these invariants and we will see that one of the most important feedback-invariants is the control analogue to the Gaussian curvature of a surface. As we will explain it, the control curvature reveals very precious information on the optimal synthesis of time optimal problems. In a second part we will construct some microlocal normal forms for time optimal control systems a…

Robust delay-dependent H∞ control of uncertain time-delay systems with mixed neutral, discrete, and distributed time-delays and Markovian switching p…

2011

Author's version of an article published in the journal: IEEE Transactions on Circuits and Systems I: Regular Papers. Also available from the publisher at: http://dx.doi.org/10.1109/tcsi.2011.2106090 The problem of robust mode-dependent delayed state feedback H ∞ control is investigated for a class of uncertain time-delay systems with Markovian switching parameters and mixed discrete, neutral, and distributed delays. Based on the LyapunovKrasovskii functional theory, new required sufficient conditions are established in terms of delay-dependent linear matrix inequalities for the stochastic stability and stabilization of the considered system using some free matrices. The desired control is …