First and second order Central Limit Theorems for the recursive computation of the invariant distribution of a Feller process

This paper studies the convergence of empirical measures of a stochastic approximation toward the invariant distribution of a Feller process. In particular, we provide a general and abstract approach to establish Central Limit Theorems (CLT) with given rate . Moreover, considering weighted empirical measures of a weak order two stochastic approximation, we show its second order convergence while the CLT for standard empirical measures has order one. We also propose various applications: First order CLT for the approximation of Markov Brownian diffusion stationary regimes with Euler scheme (where we recover existing results from literature) and second order CLT for the approximation of Brownian diffusion stationary regimes using Talay scheme (1990) of weak order two.Comment: arXiv admin note: substantial text overlap with arXiv:1703.04557, arXiv:1712.0404

Fast object detection in compressed JPEG Images

Object detection in still images has drawn a lot of attention over past few years, and with the advent of Deep Learning impressive performances have been achieved with numerous industrial applications. Most of these deep learning models rely on RGB images to localize and identify objects in the image. However in some application scenarii, images are compressed either for storage savings or fast transmission. Therefore a time consuming image decompression step is compulsory in order to apply the aforementioned deep models. To alleviate this drawback, we propose a fast deep architecture for object detection in JPEG images, one of the most widespread compression format. We train a neural network to detect objects based on the blockwise DCT (discrete cosine transform) coefficients {issued from} the JPEG compression algorithm. We modify the well-known Single Shot multibox Detector (SSD) by replacing its first layers with one convolutional layer dedicated to process the DCT inputs. Experimental evaluations on PASCAL VOC and industrial dataset comprising images of road traffic surveillance show that the model is about $2\times$ faster than regular SSD with promising detection performances. To the best of our knowledge, this paper is the first to address detection in compressed JPEG images

Computing the Kalman form

We present two algorithms for the computation of the Kalman form of a linear control system. The first one is based on the technique developed by Keller-Gehrig for the computation of the characteristic polynomial. The cost is a logarithmic number of matrix multiplications. To our knowledge, this improves the best previously known algebraic complexity by an order of magnitude. Then we also present a cubic algorithm proven to more efficient in practice.Comment: 10 page

On reflected entropy and computable cross-norm negativity: Free theories and symmetry resolution

We investigate a separability criterion based on the computable cross-norm (CCNR), and a related quantity called the CCNR negativity. We introduce a reflected version of the CCNR negativity, and discuss its connection with other well-established entanglement-related quantities, namely the reflected entropy and the operator entanglement entropy. For free fermionic and bosonic theories, we derive exact formulas in terms of two-point correlation functions, which allows for systematic numerical investigations and, in principle, analytical treatments. For systems with a global $U(1)$ symmetry, we study the symmetry-resolved reflected entropy and CCNR negativity. We provide conformal field theory (CFT) results for the charged moments in the case of adjacent intervals, finding perfect agreement with the numerics. We observe an equipartition of reflected entropies and CCNR negativities, both for free fermions and free bosons models. The first charge-dependent correction are conjectured for fermions, and worked out from the CFT calculations for bosons.Comment: 9+2 pages, 3 figure

Az űrhajósok kiválogatásának pszichológiai és szociológiai kérdései (1.)

A magyar űrkutatás és űrtevékenység – Bay Zoltán híres holdradar-kísérletétől számítva – 75 éves múltra tekint vissza. A hazai kutatóműhelyek, tudományos intézetek, sőt immáron a gazdasági szereplők képességei nemzetközi viszonylatban is kitűnnek. Magyarország számára stratégiai érdek, hogy megőrizze és fejlessze a világűrben folytatott tevékenysége kompetenciáit, erősítse pozícióit. A kormány 2021-ben fogadta el Magyarország első űrstratégiáját. E stratégiai dokumentum megállapításaival és célkitűzéseivel összhangban kulcsfontosságúvá vált egy interdiszciplináris tudásplatform létrehozása. A Hunor-program keretében, több ezer jelentkező közül választották ki azt a nyolc jelöltet, akiket jelenleg a Magyar Honvédség légiereje tesztel a kecskeméti bázison, és akik közül egy – Farkas Bertalant követve – második magyarként tehet majd űrutazást. A szerző háromrészes tanulmányában az űrhajósok kiválasztásának pszichológiai és szociológiai aspektusait elemzi

Separability and entanglement of resonating valence-bond states

We investigate separability and entanglement of Rokhsar-Kivelson (RK) states and resonating valence-bond (RVB) states. These states play a prominent role in condensed matter physics, as they can describe quantum spin liquids and quantum critical states of matter, depending on their underlying lattices. For dimer RK states on arbitrary tileable graphs, we prove the exact separability of the reduced density matrix of $k$ disconnected subsystems, implying the absence of bipartite and multipartite entanglement between the subsystems. For more general RK states with local constraints, we argue separability in the thermodynamic limit, and show that any local RK state has zero logarithmic negativity, even if the density matrix is not exactly separable. In the case of adjacent subsystems, we find an exact expression for the logarithmic negativity in terms of partition functions of the underlying statistical model. For RVB states, we show separability for disconnected subsystems up to exponentially small terms in the distance $d$ between the subsystems, and that the logarithmic negativity is exponentially suppressed with $d$. We argue that separability does hold in the scaling limit, even for arbitrarily small ratio $d/L$, where $L$ is the characteristic size of the subsystems. Our results hold for arbitrary lattices, and encompass a large class of RK and RVB states, which include certain gapped quantum spin liquids and gapless quantum critical systems.Comment: 18 pages, 8 figures, v2: new discussion on multipartite entanglement and separability, v3: minor modification

Analyse de la tâche d'un pilote de Rafale à l'aide d'une HTA étendue à la gestion des modes dégradés

International audienceCette communication présente l'adaptation de la méthode HTA pour l'étude d'une situation dynamique incertaine et coopérative : une mission militaire aérienne réalisée par un pilote de chasse à bord d'un avion Rafale. Les boucles - perception, représentation, action - caractéristiques de la gestion d'une situation dynamique sont intégrées dans la HTA sous la forme de buts de haut-niveau. La mise en évidence de plans contingents permet de rendre compte de la gestion de l'incertitude et des situations dégradées. Enfin, la coopération multiagents est décrite par un codage des tâches de communication précisant la fonction, l'objet et les acteurs impliqués. Finalement, les intérêts et les limites de l'application de la méthode HTA dans le cadre des situations dynamiques sont discutés

Apports des prospections non destructives à la connaissance du quartier artisanal antique de l'Essarté, Epomanduodurum, commune de Mathay, Doubs

National audienceThe Essarté workshop area, dating to the Classical period, is situated in the town of Mathay (Doubs). Excavated in the 1980s and 90s, it has been interpreted as an area specializing in ceramics production. This study of this area takes place in the context of an ongoing, broader project focused on the ancient town of Mandeure-Mathay (Epomanduodurum) and its surroundings, currently conducted within the framework of a PCR (collective research project). To undertake a more detailed study of the Essarté area fieldwalking surveys were carried out in 2006 and a synthesis of previous excavations, based on the available documentation, was completed in 2009. Geophysical surveys were conducted in 2009 and 2010. In addition, a LiDAR survey of Mandeure-Mathay and its surroundings realized in 2009 included the Essarté area. This paper contextualizes the data provided by excavations and aerial surveys carried in the 1980s and 90s by integrating it with the data obtained through the magnetometry survey - providing additional information on sub-surface features - and the data obtained through fieldwalking and LiDAR (Light Detection And Ranging) surveys - used to characterize the micro-topography of the terrain surface and associated materials in detail. This new study, in addition to adding details to the existing picture of the Essarté area, demonstrates that this locale was used as a burial area prior to the Roman phase of the site.L'Essarté est un quartier antique de potiers situé sur la commune de Mathay (Doubs). Il a été fouillé dans les années 1980-90. Dans le cadre d'un PCR consacré plus généralement à l'ensemble de l'agglomération antique de Mandeure-Mathay (Epomanduodurum) et aux espaces qui l'environnent, des prospections au sol ont été menées à l'Essarté en 2006, une synthèse des fouilles basée sur la documentation existante a été faite en 2009, et des prospections géophysiques ont été réalisées en 2009 et 2010. Par ailleurs, l'agglomération antique et ses alentours ont fait l'objet d'un relevé LiDAR en 2009. Cet article présente la mise en perspective des données acquises par les fouilles et par les prospections aériennes des années 1980-90 avec les informations obtenues à partir des résultats des prospections magnétiques, qui ont permis d'avoir des renseignements sur la nature du proche sous-sol, ainsi qu'à partir des prospections pédestres récentes et du relevé LiDAR (Light Detection And Ranging), qui informent sur ce qui est observable en surface, notamment sur les variations et micro-variations du relief grâce au LiDAR. Globalement, la nature du quartier antique et sa topographie ont pu être précisées, et des données nouvelles relatives à une occupation antérieure de la zone (nécropole) ont été acquises

Slope instabilities in Dolomieu crater, Réunion Island: From seismic signals to rockfall characteristics

International audienceThe seismic signals of hundreds of rockfalls within Dolomieu crater, Piton de la Fournaise volcano, Réunion Island, have been analyzed to investigate a possible link between physical rockfall-generating processes and associated seismic signal features. Moreover, indirect observation of rockfalls via the seismic signals they generate can provide useful data for studying volcanoes and the temporal variations of their structure. An increase in the number of rockfall events and their volumes might be an indicator of structural weakness and deformation of the volcano associated with potential eruptive activity. The study focuses on a 10 month period following the 6 April 2007 crater floor collapse within Dolomieu crater, from May 2007 to February 2008. For granular flows a scaling law is revealed between seismic energy and signal duration. A semiempirical approach based on both analytical analysis and numerical simulation of these flows shows that a similar scaling law exists between the difference of potential energy computed for an event and its propagation times and also emphasizes the effect of local topography on this scaling law. Simulated and observed data were compared to evaluate the proportion of potential energy dissipated in the form of seismic waves and confirm a direct link between the seismic energy and potential energy of a given granular flow. The mean ratio of seismic to potential energy is of the order of 10−4, comparable to the range of values observed in previous studies. A simple method based on these ratios is proposed to estimate the volumes of rockfalls from their seismic signal. Observed seismic energy and the frequency of rockfalls decreased at the beginning of the studied period and reached a stable level in July, thus suggesting a postcollapse relaxation time of Dolomieu crater structure of about 2 months from seismic signal analysis, which is confirmed by deformation data. The total rockfall volume over the study period is estimated to be 1.85 Mm3