Portail HAL Ensta
Not a member yet
11080 research outputs found
Sort by
Passerini–Smiles Reaction of α‐Ketophosphonates: Platform for Phospha‐Brook/Smiles Embedded Cascades
No full textInternational audienc
Sampling Parallel SOA-MZIs Configuration for All-Optical Simultaneous Frequency Down-Conversion
No full textInternational audienceIn this paper, we expound a modulation concept to contrive simultaneous frequency down-conversion based on a three parallel Semiconductor Optical Amplifier Mach-Zehnder Interferometers (SOA-MZIs) link by using a band pass sampling method in a Virtual Photonics Inc. simulator. Each SOA-MZI is deployed to achieve a down-converted signal, which has ten replicas related to the first ten harmonic ranks of the sampling signal, at the SOA-MZI outer port. Then, the admixture of the three down-converted signals yields a sampled signal, which is called a simultaneous down-converted signal that contains thirty different replicas. The positive down-conversion gains with top values are reached with the sampling parallel SOA-MZIs link. Moreover, we evaluated the quality of the parallel SOA-MZIs transmission system over orthogonal frequency division multiplexing (OFDM) complex modulated signals using the error vector magnitude values as a performance index. The utmost bit rate attained is 2 Gbit/s for OFDM modulations
Radical Alliances. Solutions and Opportunities for Organic Synthesis
No full textInternational audienc
Synthesis of analogues of complex natural products for anticancer applications
No full textInternational audienc
Etude multi-échelles de la formation de coulis frigoporteurs diphasiques pour la réfrigération secondaire
No full textWith 20% of electricity consumption worldwidel, refrigeration and air conditioning (RAC) industry is one of the most energy-intensive sector. Among the solutions to reduce RAC carbon footprint, it is possible to implement environment-friendly fluids in indirect refrigeration systems which roled is to carry thermal energy from the cold production machine (containing primary refrigerant) to the places of use. indirect refrigeration systems using secondary refrigerants thus greatly reduces primary refrigerant amount (by about a factor of 10). Currently, the use of phase change materials (PCM) in indirect refrigeration systems (to form PCM slurry) is an innovative design in development. They improve the process by increasing the energy density of the fluid. Currently, the use of phase change materials (PCMs) in secondary refrigeration systems (to form a PCM slurry) is an innovative design in full development.This study focused on a secondary refrigeration process based on the use of gas hydrate slurry as MCP. Mixed gas hydrates, which are formed with water and CO2 and cyclopentane (CP) are studied in this work. The first experiments focused on the study of four-phase equilibria (CO2, liquid water, liquid cyclopentane and hydrate). The presence of cyclopentane as a promoter to the formation of mixed CP + CO2 hydrates allows the formation of hydrates at low pressure and moderate temperature. A second study of the flow conditions of the cyclopentane hydrate slurry and the CP + CO2 mixed hydrate slurry is performed in a dynamic circulation loop at different cyclopentane fractions ranging from 3 wt% to 15 wt%. The rheological parameters (viscosity, flow behavior...) related to these two types of slurries are compared. The rheological study allowed to highlight the shear-thinning behavior of the hydrate slurry for differents cyclopentane fractions. In addition, the rheological behavior of the mixed CP + CO2 hydrate slurry showed an evolution in time. The first results of the thermal characterization at a heating tube complete this work.Avec 20% de la consommation d’électricité mondiale, l’industrie de la réfrigération et de la climatisation est l’un des secteurs les plus consommateurs d’énergie. Parmi les solutions pour réduire l’empreinte carbone dans le domaine du froid et climatisation, il est possible de mettre en œuvre des fluides neutres vis-à-vis de l’environnement dans des systèmes de réfrigération secondaire dont le rôle sera de transporter l’énergie depuis le lieu de production (contenant le réfrigérant primaire) vers les lieux d’utilisation. Actuellement l’utilisation de matériaux à changement de phase (MCP) dans les systèmes de réfrigération secondaire (pour former un coulis de MCP) est une conception innovante en plein développement.Cette étude concerne un procédé de réfrigération secondaire reposant sur l’emploi de coulis d’hydrates de gaz comme FFD. Les hydrates mixtes de gaz, qui se forment à partir d’eau et du CO2 et du cyclopentane (CP) sont étudiés dans ce travail. Les premières expériences se sont focalisées sur l’étude des équilibres quadri phasiques (CO2, eau liquide, cyclopentane liquide et hydrate). La présence du cyclopentane comme promoteur à la formation des hydrates mixtes CP + CO2 permet la formation des hydrates à basse pression et température modérée. Une deuxième étude des conditions d’écoulements du coulis d’hydrates de cyclopentane et du coulis d’hydrates mixtes CP + CO2 est réalisée dans une boucle de circulation dynamique pour différentes concentrations en cyclopentane alllant de 3wt% à 15wt%. Les paramètres rhéologiques (viscosité, comportement d’écoulement…) relatifs à ces deux types de coulis sont comparés. L’étude rhéologique a permis de mettre en évidence le comportement rhéofluidifiant du coulis d’hydrates pour des concentrations en cyclopentane. En outre, le comportement rhéologique du coulis d’hydrates mixtes CP + CO2 a montré une évolution dans le temps. Les premiers résultats de la caractérisation thermique au niveau d’un tube chauffant complètent ce travail
Seismo-acoustic wave propagation generated by the detonation of UXOs of large charge weights in a shallow water environment
No full textInternational audienceUnexploded historical ordnance (UXO) from World War II, that is discovered almost every week close to the French coast, must be destroyed quickly after discovery to ensure the safety of divers and ships. The favored destruction method is countermining, i.e., the use of a high-order detonation conducted by exploding an additional donor charge placed adjacent to the UXO. In the framework of a UXO countermining campaign conducted in the Rade d'Hyères (Mediterranean Sea, France) in December 2018, hydro-acoustic and seismic recording systems have been deployed to record the explosion-induced waves in water and the seismic signals on the shore, respectively (POSA project). In this expanded abstract, we present the main observations and focus on the impact of the shallow water environment (whose water depth is less than 50 m), and more specifically on the impact of the unconsolidated sedimentary layer, on the recorded signals induced by the detonation of charges with weights ranging from 80 to 680 kg TNT-equivalent. We also discuss the acoustic-to-seismic wave conversions
Statistical intrusion detection and eavesdropping in quantum channels with coupling: multiple-preparation and single-preparation methods
No full textInternational audienceClassical, i.e. non-quantum, communications include configurations with multiple-input multiple-output (MIMO) channels. Some associated signal processing tasks consider these channels in a symmetric way, i.e. by assigning the same role to all channel inputs, and similarly to all channel outputs. These tasks especially include channel identification/estimation and channel equalization, tightly connected with source separation. Their most challenging version is the blind one, i.e. when the receivers have (almost) no prior knowledge about the emitted signals. Other signal processing tasks consider classical communication channels in an asymmetric way. This especially includes the situation when data are sent by Emitter 1 to Receiver 1 through a main channel, and an "intruder" (including Receiver 2) interferes with that channel so as to extract information, thus performing so-called eavesdropping, while Receiver 1 may aim at detecting that intrusion. Part of the above processing tasks have been extended to quantum channels, including those that have several quantum bits (qubits) at their input and output. For such quantum channels, beyond previously reported work for symmetric scenarios, we here address asymmetric (blind and non-blind) ones, with emphasis on intrusion detection and additional comments about eavesdropping. To develop fundamental concepts, we first consider channels with exchange coupling as a toy model. We especially use the general quantum information processing framework that we recently developed, to derive new attractive intrusion detection methods based on a single preparation of each state. Finally, we discuss how the proposed methods might be extended, beyond the specific class of channels analyzed here
A proposal learning strategy on CNN architectures for targets classification
No full textInternational audienc
A four-point bending test to study both failure initiation and crack propagation at the interface of an adhesive joint
No full textInternational audienceIn this study the authors propose a test specimen developed to study both failure initiation and crack propagation at the interface with the aim to determine its strength and toughness. The two-substrate specimen used were bonded with a thin joint of structural adhesive, to conform to most of the industrial applications. Then, geometry of the specimen and parameters of the four-point bending were designed to localize failure initiation at one interface and in order to have a stable evolution of the crack propagation at this interface. This optimization work was performed using 3D Finite Element Model for an interface of metallic substrates and an industrial epoxy based adhesive. An experimental campaign was carried out on the optimized configuration of the specimen and the four-point bending flexural loading. The failure properties identified at the interface for a specific surface preparation are compared to the one characterized for “cohesive” failures on the structural adhesiv