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Circularly-Polarized Reconfigurable Transmitarray in Ka-Band with Beam Scanning and Polarization Switching Capabilities
No full textInternational audienceThe design, realization, and experimental characterization of a 400-element electronically reconfigurable transmitarray operating in the Ka-band is presented. It is based on linearly polarized unit-cells with 180° phase-shifting capability. Several sequential rotation schemes have been compared numerically to generate a circularly polarized beam over a broad frequency band, and a random distribution has been selected to mitigate spurious cross-polarized side-lobes when scanning the main beam. The 2-D electronic beam-steering capabilities of ±60° have been verified experimentally. The prototype, illuminated by a horn antenna as a focal source, exhibits a broadside gain of 20.8 dBi at 29.0 GHz and a 3-dB bandwidth of 14.6% with radiation efficiency of 58%. The axial ratio remains below 2 dB within this bandwidth. Next, a planar substrate integrated waveguide focal source array was designed in order to reduce the focal distance by about 50% and thereby significantly improve the antenna compactness, and similar radiation performance is demonstrated numerically and experimentally. © 1963-2012 IEEE
Discriminative importance weighting of augmented training data for acoustic model training
No full textAdded missing sign in equations (2) and (3) + explanation about iteration 1 in Fig. 1International audienceDNN based acoustic models require a large amount of training data. Parametric data augmentation techniques such as adding noise, reverberation, or changing the speech rate, are often employed to boost the dataset size and the ASR performance. The choice of augmentation techniques and the associated parameters has been handled heuristically so far. In this work we propose an algorithm to automatically weight data perturbed using a variety of augmentation techniques and/or parameters. The weights are learned in a discriminative fashion so as to minimize the frame error rate using the standard gradient descent algorithm in an iterative manner. Experiments were performed using the CHiME-3 dataset. Data augmentation was done by adding noise at different SNRs. A relative WER improvement of 15% was obtained with the proposed data weighting algorithm compared to the unweighted augmented dataset. Interestingly, the resulting distribution of SNRs in the weighted training set differs significantly from that of the test set
Double-Spoke Slab--Selective Ramp Pulse Design for UHF TOF MR Angiography
No full textInternational audienceRecently, the use of TOF with parallel transmission at Ultra High Field demonstrated an improvement in vessel-to-background contrast and spatial resolution. This study further investigates the in-vivo feasibility to correct for blood flow saturation effects in TOF slabs with a new double-spoke ramp pulse design optimization at 7T while mitigating in-plane TOF heterogeneities
New state estimators and communication protocol for distributed event-triggered consensus of linear multi-agent systems with bounded perturbations
No full textInternational audienceThis paper extends recent results by Garcia et al. on event-triggered communication to reach consensus in multi-agent systems. First, it studies the effect of two types of additive and bounded state perturbations on the consensus and on the communications. Second, it describes an improved agent state estimator as well as an estimator of the state estimation uncertainty to trigger communications. Convergence to consensus is studied. Simulations show the effectiveness of the proposed estimators in presence of state perturbations
Discovering associations between adverse drug events using pattern structures and ontologies
No full textInternational audienceBackground: Patient data, such as electronic health records or adverse event reporting systems, constitute an essential resource for studying Adverse Drug Events (ADEs). We explore an original approach to identify frequently associated ADEs in subgroups of patients. Results: Because ADEs have complex manifestations, we use formal concept analysis and its pattern structures, a mathematical framework that allows generalization using domain knowledge formalized in medical ontologies. Results obtained with three different settings and two different datasets show that this approach is flexible and allows extraction of association rules at various levels of generalization. Conclusions: The chosen approach permits an expressive representation of a patient ADEs. Extracted association rules point to distinct ADEs that occur in a same group of patients, and could serve as a basis for a recommandation system. The proposed representation is flexible and can be extended to make use of additional ontologies and various patient records
Nonlinear Static State Feedback for Saturated Linear Plants via a Polynomial Approach
No full textInternational audienceThe paper revisits the local exponential stabilization and global asymptotic stabilization problems of saturated linear systems using nonlinear control laws. The proposed nonlinear control law has rational dependence on a parameter σ, which is computed by solving an implicit equation depending on the state. Constructive solutions are obtained, based on a sum-of-squares formulation of the proposed conditions
Versioning and Annotation Support for Collaborative Mapping Design
No full textInternational audienceThis paper describes a versioning and annotation system for supporting collaborative, iterative design of mapping layers for digital musical instruments (DMIs). First we describe prior experiences and contexts of working on DMIs that has motivated such features in a tool, describe the current prototype implementation and then discuss future work and features that are intended to improve the capabilities of tools for new musical instrument building as well as general interactive applications that involve the design of mappings with a visual interface
Energy Optimization of D2D Communications Using Relay Devices and Data Entropy
No full textInternational audienceDevice-to-device (D2D) communications are an-nounced as a cornerstone of the next generation of wirelesscommunications (5G). They offer the promise to drasticallyreduce the energy consumption of devices (phones, tablets,etc.), and increase network coverage areas. In this paper, wepropose to study the influence of a relay device in a D2Dcommunication. We aim to show the impact of relaying on theenergy consumption. Our work provides a new perspective onthe D2D communications by integrating innovative topology inthese communications. Indeed, D2D is a local-area-based typeof communications. Then, we assume that the data transmittedby different users have a certain correlation between each other.Therefore, a new approach is to use the common entropy betweeneach D2D devices to reduce the amount of data relayed by therelay device. This minimization leads inevitably to a reduction ofthe energy consumed by the relay device, and the network. Weanalyze the optimal case (in terms of position of the relay nodeand correlation coefficient between different data) to validate theproposed topology, based on conditional entropy
Conception d’une antenne compacte de station de base pour réseaux cellulaires
No full textCellular networks undergo majors changes in theworld. Several standards have been deployed since1980. The enthusiasm of the general public quicklysaturated the first generations and the number ofservices increases for every standard. Development ofa new one is the occasion to find new ways to simplifythe radio architecture in order to relieve consumershigh quality of service.Today, this radio architecture has been simplified butbase station antennas have become more and morecritical for their size and create problems in townsspecially. Moreover, constraints from the governmentand consumers associations contest deployment ofnew base station.Works of the thesis are focused on increasing basestation antenna gain based on two differenttechnologies. Then, conception of compact radiatingelements was developed and presented through asmall array. Good results open new perspectives torealize a compact multiband base station antennathanks to new compact radiating element sized inothers frequency bands.Les réseaux cellulaires ont connu et continuent deconnaitre des évolutions majeures à travers le monde.Plusieurs standards ont été déployés par tous lesopérateurs depuis la fin des années 1980.L’engouement du grand public a vite fait saturer lespremières générations et le nombre de servicesaugmentent à chaque standard. Le développementd’un nouveau standard est l’occasion de simplifierl’architecture radio pour proposer une meilleurequalité de service (couverture radio ou débit).De nos jours, toute l’architecture a subi de grandesmodifications sauf les antennes panneaux classiquesqui posent des problèmes croissants surtout dans lescentres villes.Ce mémoire s’oriente sur la possibilité d’améliorer lesperformances de deux antennes de station de baseexistantes. Ensuite, la conception d’élémentsrayonnants compacts a été abordée afin de réduire lasurface occupée par un réseau. Sa faisabilité a étévalidée puis présentée par la réalisation d’un réseausimplifié. Les résultats encourageants obtenus à la findes travaux ouvrent de nouvelles perspectives pour laréalisation d’une antenne de station de base compactemultibande avec l’ajout de nouvelles antennescompactes dans d’autres bandes de fréquence
Carrier-Grade Performance Evaluation in Reliable Metro Networks Based on Optical Packet Switching
No full textInternational audienceIn this paper we assess the performance delivered in a metro network by two optical packet switching architectures, enabling sub-wavelength switching granularity. We compare POADM (Packet Optical Add/Drop Multiplexer) with TWIN (Time-domain Wavelength Interleaved Network). These technologies are envisaged to be deployed in the metropolitan area in order to improve bandwidth utilization and minimize energy consumption, thanks to their excellent switching granularity. In order to perform a realistic performance assessment, the study was carried out over a large set of traffic demands, for which the candidate architectures were first dimensioned taking into account network reliability. Then, the delivered data plane performance was assessed by simulation in terms of electronic packet loss, jitter and insertion delay. Two routing scenarios (anyto- any and hub-and-spoke) are mapped on a physical topology inspired from a European operator network. Simulation results show that both architectures easily achieve performance targets set by the Metro Ethernet Forum, as long as the network is properly dimensioned