Consequences of the introduction of cereal - grain legume intercrops in the supply chain. Analysis from the perspective of farmers and cooperatives

Intercropping (the simultaneous growth of 2 or more species in the same field) is one way to solve some difficulties that organic supply chain has to face. The aim of this article is to assess the consequences and the compatibility with intercrops at 2 levels: i) cropping systems of 18 farmers from north of France and ii) the logistics ofagricultural cooperatives which collect durum wheat in Midi-Pyrenees altogether with two cooperatives that already had experimented intercrops (Terrena and AgriBioUnion).The conclusions of our work is that intercrops seem a priori compatible with farmers’ cropping systems and with the presentlogistic organization of cooperatives but the main difficulty remains the feasibility and the cost in sorting out grains. Constraints and benefits of intercrops must then be analyzed more precisely at each level of the supply chain in order to collectively develop solutions

Volumetric Proper Orthogonal Decomposition of an impinging jet using SPIV measurement

Impinging jets which interact with sharp edges like slotted plates can be found in ventilation and air conditioning systems. In some cases, these configurations can be a source of desirable sounds like in musical instruments. However, they can be a source of noise in other applications such as air conditioning systems. Thus in order to reduce the noise produced from such configurations a more profound study of the flow dynamics should be implemented. All previous studies of impinging jets on a slotted plate were done in 2D. Accordingly, the objective of the present study was to reconstruct the studied volume by combining stereoscopic PIV measurements and the POD method. Consequently, an experimental set up has been developed and implemented in order to generate a flow that hits a slotted plate. On the other side, the PIV technique was used in order to study the dynamics of such a flow. The kinematic fields of twenty two parallel planes are measured by means of stereoscopic PIV. Afterwards, the analysis of the most energetic modes was obtained by the application of the snapshot POD on the kinematic fields obtained by POD. The results showed that the reconstruction of each of the planes needed only three first three modes. The reconstructed volume is obtained by an interpolation of the reconstructed planes which were phased by a trigger signal. The analysis of the vortex structures were done by the application of several vortex detection criteria

Tomographic and Time-Resolved PIV measurement of an Impinging Jet on a Slotted Plate

In order to reveal the complete topology of unsteady coherent flow structures the instantaneous measurement of the 3D velocity field is being of the great interest in fluid mechanic. Several different methods were proposed to achieve a 3D version of the technique (scanning light sheet, holography, 3D PTV). We aimed in our study to develop a 3D technique than enables to obtain the 3D kinematic field of an impinging jet by using 2D measurements. In this study and in order to validate the proposed technique [1], the tomographic particle image velocimetry technique has been applied to time resolved PIV recordings. The first step before the validation was to study the vortex shedding phenomena between the jet exit and the slotted plate. The experiments were performed at a Re = 4458 with an initial velocity U0=7m/s using three cameras Phantom V711 and a Nd: YLF LDY 300 Litron laser. In the present study, we analyzed the coherent structures organization by a 3D-velocity visualization. Both mean and fluctuating part of velocity were analyzed for several positions in z. The results has shown that a couple of vortex rolls are created downstream the flow at y/H=2

Linear model of electrical three-phase network to desing robust controller

International audienc

Linear model of electrical three-phase network to desing robust controller

International audienc

Contribution à l'analyse et la synthèse de lois de commande robustes pour la machine asynchrone

Le travail présenté dans cette thèse apporte une contribution sur les méthodes d'analyse, de commande robuste appliquées aux machines asynchrones. Le but principal qui est de trouver des correcteurs robustes vis à vis des variations paramètriques a été atteint et a engendré les contributions suivantes : Analyse avec des fonctions de Lyapunov dépendants des paramètres sur le bouclage linéarisant en présence de variations paramètriques. Développement d'une synthèse HÆ sur le modèle linéarisé avec objectifs de commande en multivariable. Utilisation d'un modèle de référence pour robustifier la linéarisation. Développement d'une synthèse mixte H2/HÆ avec modèle de référence sur le modèle de la machine bouclée par linéarisation pour éviter l'influence des variations paramètriques. Comparaison de ces différentes solutions et implantation sur un banc expérimental. L'effort de prouver expérimentalement les apports des commandes synthétisées, a nécessité la mise en œuvre d'un banc d'essai complet avec variateur industriel, cartes "temps réel" et interface logiciel.This PhD thesis concerns methods of analysis and robust control applied on induction motors. The induction machine supplied by inverter is usually assume to be a complex system.The aim of finding robust controllers was reached and has generated the following contributions : Analysis with functions of Lyapunov dependent on parameters applied to the linearizing control in the presence of parametric variations. Development of a Hinf synthesis on the linearized model with aims of order into multivariable. Presentation of the use of the reference model to improve the robustness of the lineariszation. Development of a H2/HÆ mixed synthesis with reference model on the linearized motor to avoid the influence of the parametric variations. Comparison of these various solutions and establishment on one experimental bench.POITIERS-BU Sciences (861942102) / SudocSudocFranceF

A PLL-Based Online Estimation of Induction Motor Consumption Without Electrical Measurement

This work is supported by a company wishing to develop new products in the field of energy monitoring in industry. It concerns the real-time estimation of the electrical consumption of an asynchronous motor without electrical measurement. The challenge consists of estimating the characteristic quantities of the motor (speed, torque, powers, efficiency) with only one vibratory measurement, information on the nameplate and commercial documentation available online. To obtain a real-time estimate, traditional FFT analysis is replaced by a PLL initially designed for power grid analysis. So, the second challenge is to modify this PLL for use with vibratory measurement characterized by a low signal-to-noise ratio, amplitude variations and a non-stationary behavior. A complete design and experimental tests are presented to validate the proposed approach

Soft sensor design for mechanical fault detection in PMSM at variable speed

International audienc

Commande robuste des systèmes multivariables, application à un filtre actif parallèle triphasé d'un réseau électrique basse tension

Le travail effectué dans cette thèse a pour objectif de combiner les connaissances de deux domaines de recherche : l automatique et l électronique de puissance afin de dégager une méthodologie pour contrôler un filtre actif parallèle triphasé. En effet, ce sujet est largement traité par les spécialistes de l électronique de puissance pour éliminer les harmoniques de tension et de courant sur un réseau de distribution électrique. La plupart des stratégies de commande sont basées sur la formulation du problème du filtrage actif comme un problème de suivi de consignes classiquement utilisé dans ce domaine. L approche que nous proposons est de considérer le problème comme un problème linéaire de rejet de perturbations. La modélisation linéaire du système permet la synthèse d une loi de commande robuste multivariable en vue d une stabilisation robuste et d une performance H robuste. Cette loi de commande devra permettre d éliminer les harmoniques qui apparaissent sur le réseau, et de maintenir la stabilité et la performance du système vis-à-vis les incertitudes sur les paramètres du modèle. La validité de l approche proposée est vérifiée en simulation à partir de l outil logiciel Matlab/Simulink, puis par la mise en œuvre sur un banc expérimental.The work done in this thesis aims to combine the knowledge of two research areas: the automatic control area and the power electronics area, in order to elaborate a methodology for controlling a three-phase shunt active filter system. Indeed, this subject has been widely handled by the specialists in the field of power electronics in order to eliminate voltage and current harmonics in electrical distribution networks. Most of existing control strategies of active filters have been formulated as a current reference tracking control design problem. The alternative approach that we propose is to formulate a three-phase shunt active filter as a linear perturbation rejection problem with zero references. The linearity of the mathematical model enables us to use the H control paradigm in order to design a multivariable linear robust H controller. Such a controller is able to reject harmonics generated by the nonlinear loads, and to maintain the stability and performance of the system against the variations in the physical parameters of the electric circuit. In order to validate the proposed approach, simulations are carried out in Matlab/Simulink environment, and the control laws are implemented on an experimental test bench.POITIERS-BU Sciences (861942102) / SudocSudocFranceF

Techniques de commande prédictive et floue pour les systèmes électroniques de puissance (application aux redresseurs MLI)

Cette thèse s'inscrit dans les travaux de recherche menés sur les moyens modernes, à base de l'électronique de puissance, de dépollution harmonique du réseau de distribution de l'énergie électrique. Cette pollution constitue actuellement un problème majeur surtout dans l'industrie. Elle est causée principalement par les charges non linéaires, prélevant sur le réseau des courants non sinusoïdaux. Les convertisseurs statiques, surtout les redresseurs à diodes et à thyristors, sont de nature non linéaire et représentent la principale source d'injection de courants harmoniques. Ils requièrent donc une attention particulière afin de réduire leurs taux d'harmonique en courant. Dans ce contexte, les solutions modernes préventives adoptées, en plus du filtrage actif qui représente une solution curative, consiste à remplacer les redresseurs classiques par de nouvelles structures de convertisseurs AC/DC non polluants, dont le comportement vis-à-vis du réseau est de nature résistive. Ce travail apporte une contribution à la commande du redresseur de tension à MLI à absorption de courant sinusoïdal. En effet, différentes stratégies de commande ont été développées, simulées et validées sur un banc d'essai expérimental dont le but commun est d'obtenir un réglage performant de la tension du bus continu et un prélèvement de courants sinusoïdaux. Ces stratégies sont basées soit sur le contrôle direct des courants absorbés soit sur le contrôle direct des puissances instantanées (DPC). De plus, elles sont combinées avec des commandes dites avancées, comme les approches floue et prédictive appliquées aux deux techniques de contrôle énoncées précédemment. La simulation de ces méthodes a été mise en oeuvre à l'aide du logiciel Matlab/SimulinkTM et l'implantation en temps réel a été élaborée grâce à une carte contrôleur du système dSPACE 1104.This work deals with harmonic elimination in electrical energy distribution networks. In fact, harmonic pollution has become a major field of concern in modern industry. It is usually caused by non linear loads, which draw non sinusoidal current from the network. Current harmonics are mainly caused by static converters, especially diode and thyristor rectifiers, because they have a non linear behaviour and represent the main source of currents harmonics injection. Therefore, some measures must be taken in order to reduce current harmonic distortion caused by this equipment. In this field, the advanced preventive solutions adopted, other than active filters which are curative method, is to substitute the conventional rectifiers with new structures of AC / DC non-polluting converters, which have resistive behaviour towards the network. This research work contributes to the control of PWM rectifier with sinusoidal current absorption. That is why, various control strategies have been developed for this converter in order to obtain an efficient control of the DC bus voltage and nearly sinusoidal input current waveforms. These strategies are based either on direct control of input currents or direct power control (DPC). Moreover, they are combined with advanced controls like approaches with fuzzy logic and predictive control applied to the two preceding methods. Simulations presented in this work are performed with Matlab/SimulinkTM tools, and practical implementation in real time has been done through a system controller board dSPACE 1104.POITIERS-BU Sciences (861942102) / SudocSudocFranceF