A Genotyping-by-Sequencing approach brings new insights into the population structure and local adaptation of Western Mediterranean Oaks

XIX ENBE Annual Meeting of the Portuguese Association for Evolutionary Biology, 18-19 December 2023, Lisboninfo:eu-repo/semantics/publishedVersio

Contribution à la conception de convertisseurs analogique numérique delta sigma à temps continu, des spécifications à l'implémentation. Application à un standard de télécommunication large bande.

This PhD work focuses on low pass continuous time delta sigma converters and more precisely on the difficulties linked to the realization of this kind of converters. The aim of those researches was to build up a complete method to facilitate the design of continuous time delta sigma converters. First, the selection of architectures and the computation of loop coefficients fitting the required specifications have been studied. Afterwards the impact of clock imperfections on the global performances of this kind of converters has been addressed and an analytical method allowing the estimation of the degradations introduced by clock jitter has been proposed. Those two main contributions in the domain of continuous time delta sigma converters have been integrated in a design flow going from initial specifications to tape out. Finally, this method has been used for the design of a continuous time delta sigma converter, in a CMOS 65nm technology, addressing a WLAN application.Ce travail de recherche porte sur la conversion analogique numérique delta sigma à temps continu passe-bas, et plus particulièrement sur les difficultés de réalisation de ce type de convertisseur. L'objectif global de ces recherches était la mise en place d'une méthode de conception adaptée. Dans un premier temps, le travail s'est focalisé sur le calcul d'architecture et l'obtention de coefficients adaptés à une spécification donnée. L'impact des imperfections d'horloge sur les performances de ces convertisseurs a ensuite été étudié et une méthode analytique d'estimation des dégradations introduites par l'intermédiaire de l'horloge a été proposée. Ces deux étapes clefs lors de la réalisation d'un delta sigma à temps continu ont été intégrées à un flot de conception complet allant des spécifications à l'implémentation sur silicium. Finalement, ce flot de conception a été utilisé pour réaliser un modulateur delta sigma à temps continu en technologie CMOS065 pour une application WLAN

A new analytical approach of the impact of jitter on continuous time delta sigma converters

International audienceThe performances of continuous time delta sigma converters are severely affected by clock jitter and no generic technique to predict the corresponding degradations is nowadays available. This paper presents a new analytical approach to quantify the power spectral density of jitter errors. This generic computational method can be applied to all kind of delta sigma converters. Furthermore, clock imperfections are described by means of phase noise spectrum, consequently all possible type of jitters can be taken into account. This paper also describes the temporal non ideal clock models that have been created to simulate the impact of jitter on delta sigma converters and validate the theoretical results

A new analystical approach of the impact of jitter of the continuous time delta sigma converters

The performances of continuous time delta sigma converters are severely affected by clock jitter and no generic technique to predict the corresponding degradations is nowadays available. This paper presents a new analytical approach to quantify the power spectral density of jitter errors. This generic computational method can be applied to all kind of continuous time delta sigma converters. Furthermore, clock imperfections are described by means of phase noise spectrum, consequently all possible type of jitters can be taken into account. This paper also describes the temporal non ideal clock models that have been created to simulate the impact of jitter on delta sigma converters and validate the theoretical results

Experimental study of laminar and turbulent flame speed of a spherical flame in a fan-stirred closed vessel for hydrogen safety application

International audienceThe aim of this paper is to report new experimental results on the effect of turbulence on the propagation speed of hydrogen/air flames. To do so, a new experimental setup, called the spherical bomb, has been designed and built at CNRS-ICARE laboratory. With this new setup, the effect of a given and well-characterized turbulence intensity on the increase of hydrogen/air flame speed can be investigated. This new facility consists of a spherical vessel equipped (563 mm internal diameter) equipped with 8 motors which are linked to fans inside the bomb. Fan actuation induces the generation of a turbulent flow inside the vessel prior to any ignition. The spherical bomb is equipped with 4 quartz windows (200 mm optical diameter) that allow the use of a Particle Image Velocimetry diagnostic in order to characterize the turbulence level inside the bomb. The flame propagation was recorded using a high speed camera at 19,002 frames per second. These experiments were performed for lean to stoichiometric hydrogen/air mixtures (16–20% of H2 in air), initially at ambient temperature and pressure, and for a rotation speed from 1000 to 5000 rpm. The PIV measurements showed that a homogeneous and isotropic turbulence is created with a fluctuation speed that can reach 4 m/s at 5000 rpm. © 2016 Elsevier B.V

A 120nm low power asynchronous ADC

ISBN 1-59593-137-6This paper discusses the development of a new kind of low power processing chain which dynamically adapts sampling frequency to signals. Thus, the design of an Asynchronous Analog-to-Digital Converter (A-ADC) is tackled. Its principle is based on a non-uniform sampling scheme and asynchronous technology, that allow significant activity and power savings. A test chip targetting 10-bit speech applications has been fabricated using the 120nm CMOS process from STMicroelectronics. The power consumption is lower than 180µW leading to a Figure of Merit two times better than those of classical Nyquist converters recently published

Effects of water sprays on flame propagation in hydrogen/air/steam mixtures

Different aspects of the interaction between droplets and flame propagation have been studied. First, flammability limits of H2/air/steam mixtures at 100 kPa for 3 temperatures between 358 and 383 K. the flammability domain was marginally modified by increasing the temperature. The mixtures were not flammable for H2O mol% ≥ 55. The presence of water mist in initially dry H2/air mixtures at 100 kPa and 298 K did not shift the lower flammability limit as long as the droplets density number was below a critical value. The slight shift in the limit was essentially due to the saturated water vapor pressure. The effect of dispersed large droplets (SMD = 200-250 μm) on laminar H2/air flames was also marginal except when the droplet velocity is of the same order of magnitude as the flame speed in the same direction. Non-flammable H2/air/steam mixtures at 358 K and 383 K were made explosive by aspersion with cold water spray. However, the pressure increase was limited when ignition occurred for mixtures close to the flammability limit. In this case, the burned gas bubble was rapidly dragged downward by the spray. The water mist effect on the deflagration of H2/air mixtures were studied for various equivalence ratios. With droplets diameter <10 μm, the violence of explosion was mitigated except for lean mixtures in the domain where the combustion was not complete. In this case, the turbulence generated by the spray was sufficient to increase the combustion rate. © 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved