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The authors present a resonant permittivity measurement method which works over a large microwave frequency domain, with a very small volume sample of dielectric material. The cell is a helical resonator having many modes of resonance. The shifts of resonance frequency and Q-factors are better interpreted with a bilinear function which depends on the complex permittivity of the material than by applying the classical perturbation formula. Results concerning two different catalysts which are used in the coupling oxidation methane reaction are given as a function of the temperature and the frequency to illustrate the correlation of both data sets and the differences in catalytic mechanisms.

The oxidative coupling of methane over LiMgO and BaBiO3 - x catalysts irradiated by microwaves and classically heated is reported. Enhanced selectivities in C2+ products are observed at lower temperatures under microwave conditions, especially with the LiMgO catalyst. The complex permittivity measurements of BaBiO3 - x show that the regeneration of the active oxygen species on the surface is lower under microwave irradiation than classical heating. X-ray diffraction analyses of the catalyst before and after catalytic reaction, when it is classically heated and when it is heated by microwave irradiation, corroborate these results. Therefore, the CH3− carbanions are less oxidated at the catalyst surface under microwave irradiation. On the other hand, the quenching of the output gas probably decreases the oxidation of CH°3 radicals in the gas phase when the LiMgO catalyst is irradiated by microwaves. The quenching of the output gas is a unique consequence of microwave irradiation which heats the catalyst without heating the wall of the reactor.

The oxidative coupling of methane has been studied on a (SmLiO2)0.8(CaOMgO)0.2 catalyst by using two different modes of heating: a conventional oven and a microwave irradiation set-up. The C2 selectivity obtained with microwave heating was much higher than with conventional heating especially at low conversions. This difference could arise from the reduction of oxidation products (ethane, ethylene) in the gas phase under microwave irradiation.

The effects of microwave irradiation of an alumina-supported 0.2 wt.% platinum catalyst are studied. In the case of the isomerization of hexanes, the selectivity in isomers is increased (by a factor 1.3 to 2) when the thermal treatment of the catalyst and/or the reaction are performed under the electromagnetic field. The isomer selectivity remains high even when such catalysts are subsequently tested under classical heating conditions. These permanent and profitable effects of the microwaves could be interpreted in terms of modifications of the geometric and/or electronic properties of the platinum particles. It is pointed out that the microwave irradiation could be a new and promising way for activating catalysts.

The authors give an expression of the distribution function of relaxation times associated with the universal dielectric response. The calculations are based on the derivative of the susceptibility with respect to the frequency, and leads to an integral expression which is easy to compute.

The isomerization of 2-methylpentane over a 0.2 wt% platinum dispersed on γ-alumina catalyst is studied when the catalyst is heated either by microwave irradiation or by a classical oven. The selectivity for isomerization is considerably increased, from 45 to 80%, when the catalyst has been previously treated by microwaves or when the catalytic reaction is performed under the electromagnetic field. The isomerization power of such an irradiated catalyst remains high even when it is subsequently tested according to classical conditions. It is consequently suggested that the microwaves induced durable and profitable modifications of the catalytic behaviour of alumina-supported platinum.

This paper presents an equation for calculating the effective complex permittivity of a two-component mixture made with particles of medium 2, dispersed in host medium 1. The geometrical density function which describes the mixture is deduced from the distribution function of relaxation times for the case of medium 2 consisting of metallic particles, by assuming that the dielectric response of the mixture follows the universal dielectric response.

The role of electromagnetic heating in batchwise dyeing processes has been investigated. It has been shown that electromagnetic heating offers smoother and more homogeneous heating profiles than are possible with many conventional techniques.

Les reactions d’hydrogenolyse du methylcyclopentane et d’isomerisation des hexanes sur un catalyseur de platine a 0,2% en masse supporte sur de l’alumine sont etudiees en fonction du mode de chauffage du lit catalytique, l’apport energetique se faisant soit par chauffage thermique classique soit par irradiation microonde. La distribution des produits formes au cours de la reaction d’hydrogenolyse du methylcyclopentane est identique pour les deux systemes. Par contre, lors de la reaction d’isomerisation des hexanes, la selectivite en isomeres est plus elevee lorsque la reaction a lieu en presence d’un champ microonde.

The spatial-density function which characterizes how metal particles are embedded in a dielectric host medium, and which is used in calculating the effective permittivity of the mixture according to the theory of Bergman, can be simply related to the relaxation-time distribution function which describes the frequency dependence of the permittivity of the mixture. The direct and inverse formulae, for computing one from the other are given explicitly. New basic functions can consequently be proposed to expand spatial-density functions.

Using the modulated scatterer technique allows us to measure the electromagnetic field in an applicator. The design of a new sensor modulated at 25 Hz is described. The operating conditions and the performance are presented.The sensor can be used for measuring high microwave electric fields up to 10 kV/m in an industrial applicator supplied by any industrial magnetron.

As a consequence of the BERGMAN - MILTON theory, which expresses the effective permittivity of a two phase mixture with an integral of a density function, it has been possible to evaluate the local electrical field strength inside a heterogeneous mixture. The developed formula can be used advantageously for modeling the local temperature inside a ceramic material during its microwave sintering.

Les auteurs ont etudie experimentalement la deshydratation de la zeolite 13X sous l’action d’un champ electromagnetique. Ils en discutent la modelisation et montrent que les molecules sont desorbees directement par le champ electromagnetique, independamment de la temperature que prend le solide. La loi cinetique est du premier ordre et le coefficient de vitesse est inversement proportionnel au carre de l’intensite du champ electrique applique. Le transport de l’eau dans les pores est un processus convectif ; il s’effectue sous l’effet d’une surpression qui a pu etre evaluee.Le modele precise la dependance instantanee de la permittivite complexe du systeme au cours de son evolution.

Les auteurs decrivent une installation d'irradiation des catalyseurs permettant d'etudier leur comportement sous champ electromagnetique microonde intense. Ils discutent les conditions qu'ils ont imposees pour que les catalyseurs soient irradies de facon homogene, et les precautions prises pour mesurer la temperature en presence du champ electromagnetique. Ils decrivent le systeme de contre reaction qui stabilise celle-ci autour d'une valeur de consigne choisie a l'avance. L'efficacite et la precision du servo-mecanisme sont illustrees par plusieurs exemples.

The quasi-stationary state of microwave evaporation of a polar liquid is studied experimentally. When the energy supplied by the field to the interface is larger than the heat flux exchanged with the surroundings, the rate of evaporation is then proportional to the microwave power absorbed and can be calculated simply by dividing the power by the standard value of the latent heat of evaporation. When the field is low, the energy balance does not govern the process; the irreversibility must be taken into account.

Heat transfer between microwave heated granular material and a surrounding moving gas is both theoretically and experimentally studied. When the microwave field is homogenous, the temperature of the material can be well estimated from the gas temperature at the output and controlled through its variations. Chemical reactors heated by an inhomogeneous microwave field are also studied. Two elementary models are considered. The behavior of a long reactor, for which the travelling wave and the fluid flow have the same direction, may not be temperature stable.

Les auteurs discutent la precision des methodes de mesure de la permittivite dielectrique des milieux solides-solutions, en vue de suivre les reactions electrochimiques de la flottation des minerais. Ils proposent d'utiliser un voltmetre vectoriel, une cellule coaxiale et de combiner deux circuits de mesure pour couvrir le domaine 1-1000 MHz avec la meilleure precision. La methode peut etre automatisee comme si elle etait unique.

The authors have studied the drying of cellulose particles under microwave irradiation. They consider the drying rate, temperature and complex permittivity of cellulose under various experimental conditions. A simple model is proposed, based on a first order kinetics law, the rate constant of which depends linearly on the square of the applied electric field. They suggest that water is directly removed from the surface of cellulose by an electromagnetic field independently of the temperature.

Donnees sur la deshydratation d'un zeolite 13X dans un champ electromagnetique, qui entraine une desorption directe des molecules d'eau

The temperature dependence of density d, electric permittivity ϵs and nonlinear high field dielectric variation Δϵ are reported for various benzonitrile-alkane solutions. For the benzonitrile-isooctane mixtures which exhibit a phase separation in the considered temperature range, the phase diagram has been obtained. In the “homogeneous” one phase region, significant deviations from the normal temperature dependence of d, ϵ0, Δϵ have been observed and characterize a precritical region of several degrees C above the consolute temperature. These results support the hypothesis of strong precritical orientational interactions or local ordering phenomena. The precritical dielectric behaviour of the benzonitrile-isooctane system is shown to be very different from those of nitrobenzene-alkane or aniline-alkane mixtures.

The method of studying molecular association by the use of Piekara factor (ΔIµ/E2) measurements together with electric permittivity (Iµ) is applied to the conformational equilibria in the liquid phase of 1,2-dichloroethane and dimethyl carbonate at several temperatures. Dipole moments of the gauche conformer in the first molecule as well as the temperature and solvent dependence of the equilibrium constant are in good agreement with other data. Results on dimethyl carbonate indicate the presence of 3 conformers in the liquid; the equilibria are studied by assuming values for the dipole moments.

A numerical procedure for calculating the steady‐state temperature distribution generated by microwave absorption is described. The procedure can be applied to the case of material for which the permittivity is nonlinearly temperature dependent and can be used to simulate the conditions when temperature runaway occurs. The criteria for temperature runaway are explicitly given for a cylindrical sample which is irradiated with a uniform electric field and is simultaneously cooled by convection. The results illustrate the method of predicting runaway and avoiding it by changing the experimental conditions as a function of the characteristics of the irradiated materials.

By simultaneously measuring the total input and reflected power and the intensity of the local field inside a resonant applicator, it is possible first to estimate the effective microwave field to which the material is exposed, and second, to control the microwave energy dissipated in the heated or transformed material. The instantaneous dielectric behaviour depending on the temperature or on the fields, or on the transformation stage, is also derived. Some characteristic curves, which illustrate thermal hysteresis during a given heating process are shown.

A closed-groove guide type cavity is described. Its resonance mode is a quasi-unique TE11 mode. A large diameter cylindrical dielectric sample may be introduced into the cavity still conserving a high quality factor which is a necessary condition in order to obtain a large field amplification factor.The field profile along the sample axis is adjustable and may be asymmetric. Coupling devices are discussed and experimental details are given.

Groove guides have been known for many years. No practical microwave circuits have yet been described although these types of transmission lines could be used in many cases. This paper discusses the physical realizability of some wide band designs such as matched load, directional coupler, hybrid coupler, bend and phase shifter. Both closed and open groove guides have been investigated. Optical type components seem to be inappropriate for groove guide transmission. The best way to design components for these guides is to adapt those of standard rectangular guides, which perturb only theRffields in the vicinity of the narrow walls and to optimize the dimensions of the groove structure as a function of the losses and the symmetry of the induced spurious modes.

Direct calorimetric evaluation of the microwave loss of dielectrics is possible for granular materials. A cylindrical sample is heated by the microwave field of an incident wave in a rectangular guide and simultaneously cooled by a gas flowing through the bed.A mathematical model describing the energy balance and the heat transfer between the microwaves, the materials and the gas is proposed. It is shown that it is possible to determine, simultaneously, the temperature of the material and its microwave dielectric loss from the measurement of the exhaust gas temperature when thermal equilibrium occurs.

The behaviour of a material in a microwave field is di-rectly related to the temperature dependence of the imaginary part of the permittivity of a material. According to the conditions of thermal evacuation chosen, for example convection, its heating is either stable or unstable. For some materials, a critical temperature can be defined which represents an upper limit beyond which the heating is unstable whatever the convective heat transfers. The optimal conditions which can be obtained through the use of an automatic regulation of the heating are, as a consequence, determined. The microwave heating of EPDM rubber is treated as an example.

A modification of Onsager's model taking into account molecular anisotropy is proposed for mixtures of polar liquids. Two formulae giving the concentration dependence of the electric permittivity and its variations under the influence of strong electric fields (dielectric saturation) are derived.Comparison with experimental results for several mixtures shows that the variation of the dipole moments determined with these formulae over the whole range of concentration of a polar compound dissolved in a non-polar as well as in a polar solvent is less than 5 %. An application to the study of molecular association is proposed.

The molecular theory of dielectric properties of liquid mixtures proposed earlier is extended to cases in which the components of the liquid interact chemically.The chemical equilibrium modifies the non-linear behaviour. The resulting equation provides the possibility of adding non-linear measurements to ordinary dielectric studies of associated liquids and therefore to investigate molecular interactions in more detail.The study of pyridine + chloroform mixtures is carried out as an example. Variations of equiibrium constant with the electric permittivity of the liquid are observed. They explain discrepancies between results obtained by different techniques (i.r., n.m.r.). Variation of the electrostatic part of the solvation energy explains this phenomenon satisfactorily.

A groove guide cell for Stark modulation spectroscopy has been constructed and tested. This structure with quasi-unique mode propagation between two isolated plates is well adapted to application of a modulation voltage. The insertion losses are low (0.6 dB for a 3-m-long cell, and R band) and the cell is free of internal reflection. A metallic casing enclosing the plates acts as a shield against electrical interference, prevents low-voltage breakdown, and reduces wall adsorption of the gas. The performance of the cell is not affected by temperature variation (-80 degrees to 25 degrees C). A high sensitivity has been obtained by converting the cell into a 3-m-long, high-Q cavity. This type of cell appears to particularly recommend itself for use in intensity measurements, broadband spectroscopy, analytical studies, and high frequency range work.

Dipole moment techniques and the non-linear dielectric effect have been applied to the study of environmental influences on the conformational equilibrium in dilute solutions of succinonitrile (1,2-dicyanoethane). The trans–gauche equilibrium constant K and the dipole moment of the gauche conformer were simultaneously and unequivocally determined in the temperature range from 288 to 318 K. The enthalpy and entropy of the reaction were determined as a function of the dielectric permittivity of the solvent and indicated enhanced stability of the gauche form in polar environments. The effect is interpreted in terms of electrostatic solvation energy. The role of the orientation of the solvent molecules in the field created by the dipolar conformer outside the cavity is emphasized.

Ce mémoire a été créé à la fin de mes deux années de formation au Master Ingénierie de la Santé parcours Prévention des Risques et des Nuisances Technologiques. Il présente les principales missions effectuées au cours de ces deux années d’alternance au sein du Groupe Suivi de Chantier Sécurité au CEA Cadarache. Ma principale mission a été, la création et le développement d’un processus de formation pour l’intervention de Formation Local de Sécurité (FLS) au sein d’un chantier amiante. Ma seconde mission a consisté, en la création de tableau de bord sécurité permettant le suivi des différents indicateurs sécurité sur les chantiers de la Direction de l'Ingénierie et de la Maîtrise d’œuvre des Projets (DIMP). Chacune des missions sera développée pour permettre au lecteur de comprendre l’objectif, la réflexion et la méthodologie utilisée pour réussir ces missions.

In a context of deep restructuring initiated by ADF Group in January 2018, the manufacturing direction, which gathers the company’s manufacturing workshop, aspires to transform in an efficient way the certification process.Indeed, for many years, the company was organized around three main reference, sometimes redundant : ISO 9001 for the Quality Management, L’ISO 14001 for the Environmental Management, Le MASE for the Security Management. In this prospect, the manufacturing division would like to take advantage of the new reference about health and security at work: the ISO 45001.Indeed this new standard meets higher requirements compared to ISO referential being used at ADF. With all these innovations, the representatives of the manufacturing department have submitted the possibility of setting up a unique Integrated Management System built according to the principles of the ISO standards.For this purpose, this report presents a feasibility study on the deployment of this new standard in order to allow the directors to make a decision.; Dans un contexte de restructuration profonde du Groupe ADF initiée en Janvier 2018, la Direction Manufacturing, qui regroupe les ateliers de fabrication de l’entreprise, ambitionne de rendre son ingénierie de certification efficiente.Effectivement, le système de pilotage de la société est, depuis toujours, organisé autour de trois référentiels qui ont tendance à se juxtaposer entre eux : L’ISO 9001 pour le Management de la Qualité, L’ISO 14001 pour le Management de l’Environnement, Le MASE pour le Management de la Sécurité.Dans cette perspective, la Direction Manufacturing souhaite profiter de la parution, en Mars 2018, d’un nouveau référentiel relatif aux thématiques de la Santé et de la Sécurité au Travail : l’ISO 45001. En effet, cette norme internationale, fruit de plusieurs années de gestation, possède la même structure de haut niveau HLS (High Level Structure) que les autres référentiels ISO appliqués au sein de l’entreprise.Forts de toutes ces innovations, les représentants de la Direction Manufacturing ont soumis la possibilité de mettre en place un Système de Management Intégré Unique, bâti selon les principes des présentes normes ISO.A cet effet, ce mémoire d’alternance présente une étude de faisabilité quant au déploiement d’une telle démarche afin de permettre aux Dirigeants de prendre une décision en toute connaissance de cause.