Search results for " Rob"
showing 10 items of 689 documents
Identifying legitimate Web users and bots with different traffic profiles — an Information Bottleneck approach
2020
Abstract Recent studies reported that about half of Web users nowadays are intelligent agents (Web bots). Many bots are impersonators operating at a very high sophistication level, trying to emulate navigational behaviors of legitimate users (humans). Moreover, bot technology continues to evolve which makes bot detection even harder. To deal with this problem, many advanced methods for differentiating bots from humans have been proposed, a large part of which relies on supervised machine learning techniques. In this paper, we propose a novel approach to identify various profiles of bots and humans which combines feature selection and unsupervised learning of HTTP-level traffic patterns to d…
Expressing forest origins in the chemical composition of cooperage oak woods and corresponding wines by using FTICR-MS.
2008
A non-targeted, ultra-high-resolution mass spectrometric, direct analysis of oak-wood extracts from two species (Quercus robur L. and Quercus petraea Liebl.) from three French forests, and of a wine aged in barrels derived therefrom has been performed to identify families of metabolites that could discriminate both the species and the geographical origin of woods. From 12 T ultra-high-resolution Fourier transform ion cyclotron resonance mass spectra of wood extracts, hundreds of mass signals were identified as possible significant biomarkers of the two species, with phenolic and carbohydrate moieties leading the differentiation between Q. robur and Q. petraea, respectively, as corroborated …
Zvaigžņotā Debess: 2008, Vasara
2008
Latvijas Zinātņu akadēmija, Latvijas Universitāte
Zvaigžņotā Debess: 2004, Rudens (185)
2004
Contents: L.Kondraševa and I.Zimina. New Riga Planetarium ; I.Rabinovičs. Remembering Fricis Blumbahs ; N.Cimahoviča. 50 cm Reflector Constructed in Riga ; J.Tambergs. Problems of Dialogue between Quantum Mechanics and Theology. A.Alksnis, Z.Alksne. The Sloan Great Wall ; A.Balklavs. Radio Galaxy – Emitter of Very High Energy Gamma-Rays ; A.Balklavs. Cosmic Objects in Photos – 2 ; A.Balklavs. New Assessments of Fine-Structure Constant Variability ; N.Cimahoviča. Dark Electric Matter Objects Around Us ; A.Balklavs. New Data on the Solar Granulation ; J.Jaunbergs. The Sinking Cliffs on Io ; D.Krieviņš. Space Launchers of Early XXI Century ; M.Sudārs. SpaceShipOne Closest to X-Prize ; J.Harja.…
Optimal control of spin-systems: Applications to Nuclear Magnetic Resonance and Quantum Information
2016
The goal of this thesis is to apply the optimal control theory to Nuclear Magnetic Resonance and Quantum Information. In a first step, we introduce the different topics and the dynamics of the analyzed systems. We give the necessary tools to use the Pontryagin Maximum Principle, and also an optimization algorithm, namely GRAPE. The first work is an application of the PMP to the control of a three-spin chain with unequal couplings. We continue with the study of a classical problem called "the tennis racket effect", which is a non-linear phenomenon occuring during the free rotation of a three-dimensional rigid body. We use the results in the following chapter to determine some control laws fo…
Etude de caméras sphériques : du traitement des images aux applications en robotique
2012
La vision omnidirectionnelle permet de percevoir l'environnement sur 360◦. C'est un atout considérable pour un robot mobile puisque grâce à cette particularité, il peut tirer parti d'une information globale de la scène à tout moment. Les premières recherches allant dans ce sens remontent en 1990 avec les travaux de Yasushi Yagi qui a proposé d'utiliser un dispositif nommé COPIS en associant une caméra perspective et un miroir conique pour obtenir une vue panoramique de la scène. En 1995, Mouaddib et Pégard présentent un procédé similaire pour localiser un robot dans son environnement. Bien que ce système possède des avantages pour la localisation, il se révèle peu adéquat pour reconstruire …
Estimation de mouvement d'un système stéréoscopique hybride à partir des droites
2010
We present a motion estimation approach for hybrid stereo rigs using line images. The proposed method can be applied to a hybrid system built up from any single view point (SVP) cameras such as perspective, central catadioptric and fisheye cameras. Such configuration combines advantageous characteristics of different types of cameras. Images captured by SVP imaging devices may be mapped to spherical images using the unified projection model. It is possible to recover the camera orientations using vanishing points of parallel line sets. We then estimate the translations from known rotations and line images on the spheres. The algorithm has been validated on simulated data and real images tak…
Deep Reinforcement Learning with Omnidirectional Images: application to UAV Navigation in Forests
2022
Deep Reinforcement Learning (DRL) is highly efficient for solving complex tasks such as drone obstacle avoidance using cameras. However, these methods are often limited by the camera perception capabilities. In this paper, we demonstrate that point-goal navigation performances can be improved by using cameras with a wider Field-Of-View (FOV). To this end, we present a DRL solution based on equirectangular images and demonstrates its relevance, especially compared to its perspective version. Several visual modalities are compared: ground truth depth, RGB, and depth directly estimated from these 360°R GB images using Deep Learning methods. Next, we propose a spherical adaptation to take into …
Optimal control and shortcuts to adiabaticity techniques in linear and non-linear systems : from ion cyclotron resonance to nuclear magnetic resonance
2021
The goal of our research is to develop efficient and robust control protocols for classical and quantum systems. To this end, we have applied optimal control theory (OCT) and shortcuts to adiabaticity (STA) with inverse engineering and motion planning approaches in three different examples, which are RC (Resistor Capacitor) circuits, Fourier Transform-Ion Cyclotron Resonance (FT-ICR), and Nuclear Magnetic Resonance (NMR). Some of our results are not limited to these systems but are rather general. We apply OCT and STA with an inverse engineering approach to control the time-evolution of the charge on a capacitor. We show that OCT is a member of the family of STA solutions. In order to contr…
Chlorine flavor perception and neutralization in drinking water
2010
For water suppliers, using chlorine is necessary to ensure water bacteriological quality from the treatment plant to the consumers’ tap. However, chlorine flavour is one of the most common reasons advocated for choosing tap water alternatives as drinking water. As a consequence, the putative link between chlorine flavour perception and tap water consumption is an issue in drinking water habits studies. Since the sensory mechanisms involved in chlorine flavour perception remained largely unknown, the main objective of this thesis work was to first highlight those mechanisms and then to identify potential lever chlorine flavour sensory neutralisation.In a first step, we demonstrated that hypo…