Partial Server Pooling in Delay Systems

Accepted for publication in ACM ToMPECSWe consider a strategic resource pooling interaction between two service providers, each of which is modelled as a multi-server queue. The traditional full resource pooling mechanism, while improving the overall system performance measure, may not always benefit the providers individually. For rational service providers, there will therefore be no incentive to form a stable coalition. We address this issue by proposing three partial sharing mechanisms: two of these, PPDS and PPR, allow each provider to designate a certain number of servers to potentially serve jobs of the other provider, while the third mechanism, DQL, maintains an upper bound on the difference between occupancies of the two queues. We determine the probability of waiting for each of the three mechanisms and show through several numerical examples that their Pareto frontiers are non-empty. In particular, this shows that the proposed partial pooling mechanisms are individually beneficial to both providers and incentivize coalition formation in all situations. Finally, we apply bargaining theory to determine the operating point on the Pareto frontier

Low-Frequency Noise Measurements and Applications: Low-Frequency Noise Metrology For The Development of High-Frequency Technologies and For High Purity Signal Generation

International audienceThis presentation concerns the metrology and applications of low frequency noise in the field of very high frequency electronics. Noise metrology has its own constraints, and its own mathematical relationships to translate the fine mechanisms that define the electronic detection thresholds. The presentation will take place in two parts: one dedicated to the metrology of LF noise (LFN) measurements and the other related to their applications.The optimization and definition of an experimental device for the LFN depend on its specifications, which itself depends on the targeted limits to be measured or the ease of use for the targeted buyer. The definition of the measurement setup (and their associated equations), the compromises of settings (gain, bandwidth, RF-DC decoupling and current and impedance levels) are given by the presentation of different setups. A comparison of the advantages, drawbacks and limitations is given between home-made and commercial setups. User-friendly ease of use and detection noise floor are primarily defined by the trade-off between the ability to drive the DC signal generator or to bias the DUT from batteries. Many performances that define the quality of the LFN measurement arise from these RF-DC decoupling considerations.The second part of the presentation focuses on the applications of these LF noise measurements; it distinguishes the design of RF circuits from the study of noise sources and their evolution during the application of stresses (DC, Thermal, RF) for reliability studies.The design of high purity oscillators (MIC and MMIC) is a major concern for telecom, radar or radiometer applications. This presentation provides some intuitive design guidelines for BiCMOS (VCO MMIC) and GaN (fixed oscillator MIC and VCO) technologies. Phase noise is defined as the distance between the electrical power of the carrier (signal) and the noise at a given frequency of the carrier. SiGe technology is the best choice when it comes to LF noise and its NL conversion of phase noise, but GaN technologies offer an increased carrier signal by one to two decades and can also be considered despite higher LF spectra.The last part of the presentation concerns the use of LFN measurement to locate defects within an active device (HBT, HEMT). It also presents the use of noise spectroscopy to study the dependence of a defect versus the application of a stress (evolution of the spectra and specific monitoring of the electrical signature of the noise). The LFN represents a powerful tool to develop reliability studies, since it represents a non-invasive measurement (however, we need to DC bias the device and likely to perform measurements at different temperatures for the Arrhenius plots!). Chosen case of study are given as illustrative purpose on both SiGe HBT technologies and GaN HEMT technologies

Vers un changement de paradigme dans les dispositifs d'ouverture sociale et territoriale ? Présentation du dispositif expérimental « Horizon INSA »

International audienceVers un changement de paradigme dans les dispositifs d'ouverture sociale et territoriale ? Présentation du dispositif expérimental « Horizon INSA

IngéPLUS, donner de l'ambition aux jeunes de milieux modestes dans les filières techniques et agricoles

International audienceIngéPLUS, donner de l'ambition aux jeunes de milieux modestes dans les filières techniques et agricole

Experimental Validation of Sensitivity-Aware Trajectory Planning for a Quadrotor UAV Under Parametric Uncertainty

International audienceIn this work, we provide an experimental vali-dation of the recent concepts of closed-loop state and inputsensitivity in the context of robust flight control for a quadrotor(UAV) equipped with the popular PX4 controller. Our objectiveis to experimentally assess how the optimization of the referencetrajectory w.r.t. these sensitivity metrics can improve the closed-loop system performance against model uncertainties commonlyaffecting the quadrotor systems. To accomplish this, we presenta series of experiments designed to validate our optimizationapproach on two distinct trajectories, with the primary aimof assessing its precision in guiding the quadrotor through thecenter of a window at relatively high speeds. This approachprovides some interesting insights for increasing the closed-loop robustness of the robot state and inputs against physicalparametric uncertainties that may degrade the system’s perfor-mance

Extending Guiding Vector Field to track unbounded UAV paths

International audienceA recent advance in vector field path following is the introduction of the Parametric Guiding Vector Field method. It allows for singularity-free vector fields with strong convergence guarantees, usable even for self-intersecting paths. However, the method requires significant gain tuning for practical use. In particular, for unbounded paths, the gains will inevitably become ill-suited for efficient path following. We propose a method to overcome this issue by introducing a dynamic step adaptation strategy, which provides additional normalization properties to the field. This allows the following of unbounded curves and reduces the number of gains to tune. The proposed improvements are verified in simulations using the PaparazziUAV software

Transverse and longitudinal magnons in the strongly anisotropic antiferromagnet FePSe 3

International audienc

Describing carbons

International audienc

Tuning the spin-orbit coupling, magnetic proximity, and band hybridization in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Fe(001)</mml:mi><mml:mtext>/</mml:mtext><mml:mi>MgO</mml:mi><mml:mtext>/</mml:mtext><mml:msub><mml:mi>MoS</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> multilayers

International audienceWe present first-principles calculations of the electronic structure and spin texture of a MoS$_{2}$ monolayer in Fe/MgO/MoS$_{2}$ multilayers. These metal/insulator/semiconductor stackings are subject to an electron transfer from the Fe layer to the MoS$_{2}$ sheet, giving rise to a two-dimensional (2D) electron gas, the density of which depends on the MgO layer thickness. We describe the consequences of this electron transfer and of the magnetic proximity effect on the occupation of the conduction bands of the MoS$_{2}$ layer, on the nature of its band gap, and on the splitting and dispersion of its valence bands near the Γ point of the 2D Brillouin zone. The spin splitting and spin texture are reproduced and understood by an effective Hamiltonian, which includes Rashba, Dresselhaus, and Zeeman effects. We finally show that the splitting of the MoS$_{2}$ valence bands induced near Γ by the spin-orbit coupling is rather different when Fe is replaced by a nonmagnetic transition metal such as vanadium

Overpressure sensing through acousto-optics: a comparison between a self-mixing interferometer and an all-fiber Michelson interferometer

International audienceRecent studies have shown that a compact self-mixing interferometer can be used for the characterization of shock waves.It measures dynamically (&gt; 10 MHz) the changes in the refractive index induced by the shock wave. Associated to anappropriate acousto-optic model, the pressure profile is computed with a 34 mbar resolution. In the present work, wecompare shock wave induced refractive index variations measurements by another method using a Michelson-type fiber-optic interferometer with phase analysis that has been developed for Photonic Doppler Velocimetry applications. Theoutput signals of this system are processed in triature, which consists in analyzing the phase shift between the threeinterferometric signals. This bulkier system provides, in theory, a better resolution than the self-mixing interferometrysensing scheme. In the present paper, we compare these two optical methods to measure a shock wave pressure throughexperiments that were carried out with an open shock tube instrumented with commercial, bandwidth limited, pressuresensors. This configuration creates a spherical shock wave similar to those observed during on-field experiments withexplosives. We describe the two measurement systems and the experimental setup design used for overpressurecharacterizations. Both sensing approaches have been carried out in the same experimental conditions and with shock wavepressure peak amplitudes of a few bars. We detail the two types of signal processing and we discuss the results obtainedwith the two optical methods, which are also compared to a piezoelectric reference sensor