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Integrated photon pairs source based on counter-propagating spontaneous four wave mixing in a silicon nitride microring resonator
No full textInternational audienceWe report the design of an innovative visible-telecom photon pair source based on counter-propagating spontaneous four wave mixing (CP-SFWM) in a silicon nitride microring resonator. Unlike previous designs, the proposed integrated source achieves automatic phase matching, eliminating the need for dispersion engineering. By employing two lasers at wavelengths of 800 nm and 1550 nm as pumps on opposite ends of the bus waveguides, the resonator generates signal and idler photons at the same wavelengths as the pumps, but propagating in opposite directions. The photon pairs are produced in high-quality factor resonant modes, exhibiting a purity of 1, a brightness of 118.70pairs⋅s −1 ⋅mW −2 , and bandwidths of 157.9 MHz and 79.7 MHz for signal and idler photons, respectively. Our proposal outperforms previous CP-SFWM designs in terms of spectral properties of the photon pairs, emission rate, and scalability, making it an interesting alternative for the implementation of integrated photon pair sources for photonic networks
Changing the perspective of system crowding evaluation using a new congestion measure: application to the Emergency Department
No full textInternational audienceSystem crowding relates to the general congestion phenomenon of clients, products or patients waiting concurrently, and its adequate representation and measurement is a key step in the monitoring and optimization of system performances in response to an arrival demand. Traditional crowding and queuing measures such as occupation and waiting time are insufficiently studied in a data-driven context, especially with their transient behaviors on a short temporal scale. Furthermore, central to the study of Emergency Department systems, crowding scores suffer from a lack of interpretability, statistical relevance and extensibility to other types of systems. As such, this study introduces a new congestion measure based on the ratio of arrival and departure load given a specific time window to characterize system crowding. A mathematical framework is proposed and used to perform a 3-part evaluation and comparison on the new and traditional measures with their large temporal scale sample path properties, their short temporal scale fluid limit modelled properties and with a case study on a regional Emergency Department to illustrate and confirm the proven properties. The results, in the form of mathematical properties and correlations, show that this new measure is more pertinent to the tracking of crowding from a system perspective, notably service performances on a local scale, compared to other measures. Through this congestion measure and its characterization with a fluid limit model, this study proposes an alternative approach and takes a first step toward a new data-driven paradigm to better monitor, forecast and optimize system crowding
Understanding the changes in railway maintenance work: a sociotechnical perspective
No full textInternational audienceRailway maintenance work is relatively unknown to the general public, and sociologists have shown little interest in it. It is an outdoor job, punctuated by interventions, equipped with a lot of artifacts and distributed on the rails. This paper presents my PhD work, at the intersection between the concerns of the sociology of work, concerned with studying and characterizing this professional activity, and the CSCW, particularly around the method of technology probes and discussions between ethnography and design
La gravure plasma, une étape critique dans la technologie SiC. Mécanismes physico-chimiques et applications
No full textInternational audienceLe SiC est un des semi-conducteurs à large bande interdite présentant une certaine maturité technologique. Des composants de puissance sont aujourd’hui commercialisé en SiC. Grâce à l'amélioration de la qualité des substrats disponibles aujourd’hui en SiC d'autres applications sont envisageables, notamment en nanophotonique et technologie quantique.La gravure plasma est une étape clé dans la fabrication et la définition de l'architecture des composants SiC, la forte liaison inter-atomique ne permettant pas d'envisager des gravures classiques par voie humides.Les nouvelles applications ou architectures de composants envisagés aujourd’hui demandent d’utiliser cette technique au-delà des procédés développés pour les composants de puissance commercialisés. A titre d’exemple on peut mentionner, des via très profondes qui sont nécessaires pour la reprise de contacts ou la gravure latérales pour isoler des structures photoniques
Study of hydrogen silsesquioxane mechanism via environmental transmission electron microscopy and preparation of highly resonant Si@Au particles
No full textInternational audienceCrystalline silicon is one of the best-known dielectric materials for manipulating visible light that can achieve high transmission efficiency..
Statistical Correlation as a Forensic Feature to Mitigate the Cover-Source Mismatch
No full textInternational audienceThe present paper deals with the cover-source mismatch (CSM) problem in operational steganalysis. It first investigates the distribution of the noise in natural images, and shows how this property can be used to build a fingerprint of the cover-source, to address the issue of source identification from a single image. In particular, fingerprints from different noise extraction techniques are studied. Results show that these fingerprints can be complementary. The method proposed in the present paper aggregates them in a unique forensic feature to build a more accurate source identification algorithm than when using steganalysis features, such as the discrete cosine transform residual (DCTR). Last, the paper exploits the proposed forensic tool to mitigate CSM via "atomistic steganalysis". Used together with steganalysis methods, experimental results highlight the superiority of our approach, as compared to other atomistic mitigation strategies. The relevancy of these results is further studied on out-of-camera images coming from Flickr and the ALASKA dataset. We show that for some devices, our approach gives results superior to the omniscient scenario
Chapitre 5 : Fabrication additive : le recyclage local de plastique
No full textInternational audienceCe chapitre souligne la nécessité d’adapter la manière d’évaluer les projets industriels émergents afin d’intégrer une évaluation plus holistique, qui dépasse les considérations purement économiques. Ce chapitre a pour but d’explorer la faisabilité en phase amont d’un nouveau système de recyclage distribué de plastique par la fabrication additive intégrant à la fois les dimensions économique et environnementale. Pour cela, une démarche méthodologique de quatre phases est proposée. La démarche proposée est appliquée au cas du Green FabLab, un démonstrateur académique conçu et mis en place au sein du Laboratoire ERPI de l’Université de Lorraine en interaction avec son écosystème territorial. L’approche proposée permet de mettre en évidence des impacts positifs et négatifs qui enrichissent le processus de prise de décision des parties prenantes d’un tel projet
An integrated economic production quantity model with shortages considering energy utilization in production and warehousing
No full textInternational audienceThis article presents a mathematical analysis of the effects of shortages in an integrated inventory model that considers energy utilization in manufacturing and warehousing. A Non-Linear Programming model is proposed for the Energy-Economic Production Quantity with Shortages problem. A solution procedure is proposed to minimize total cost by analyzing different shortage policies (full backorder, partial backorder, and full lost sale). Numerical examples illustrate the significance of integrating energy consumption components in inventory modeling, particularly in the context of rising energy prices. Accepting shortages reduces average inventory levels, decreases warehousing energy costs and achieves overall cost minimization. Full backorder policy do not reduce energy consumption in production, highlighting partial backorder policy as the optimal choice from both economic and environmental perspectives. Sensitivity analysis highlights the significant influence of model parameters on total costs and energy components. The impact of energy unit cost is particularly noteworthy given increasing energy demand and supply disruptions. These findings underscore the importance of considering energy consumption and associated costs in supply chain operations, emphasizing the study’s role in addressing these challenges
COMMENT ANALYSER LE CHANGEMENT TECHNOLOGIQUE DANS LES ORGANISATIONS ? UN REGARD RÉTROSPECTIF SUR LES PUBLICATIONS DE L’ANACT (1973-2023)
No full textInternational audienceL e changement technologique est au cœur des missions de l’Anact depuis sa création en 1973. De l’introduction des machines-outils à commande numérique à l’intelligence artificielle, en passant par les progiciels de gestion ou l’usage d’Internet, l’Anact s’attache, depuis 50 ans, à comprendre les transformations technologiques, leurs enjeux en termes de conditions de travail et plus largement leurs implications organisationnelles, économiques et sociales. Ce regard a-t-il évolué depuis 5 ans ? A-t-il connu des inflexions à mesure que les technologies sont apparues ou que leur perception dans la sphère sociale ou académique a évolué ? Tel est l’objet de cet article qui s’appuie sur une analyse d’un large échantillon de publications de l’Anact portant sur le sujet, pour en décrire le contenu et donner à voir leurs évolutions au cours du temps