316 research outputs found
Alternative architecture of Cu(In,Ga)Se2 based thin film photovoltaics modules
No full textUn des principaux freins au développement industriel de la filière photovoltaïque à base de couches minces de Cu(In,Ga)Se2 (CIGSe) est son manque de maturité technologique, alors que les rendements atteints des cellules n’ont jamais été aussi élevés, à savoir 23,3% à l’échelle du laboratoire. Ce travail de thèse propose de lever un des verrous technologiques identifié à savoir un écart important entre les performances des cellules et celles des modules. Ces pertes sont inhérentes à l’interconnexion monolithique (réalisée à l’aide des gravures P1, P2 et P3 de manière standard) qui induit (i) une réduction de la surface active des panneaux, (ii) des pertes optiques ainsi que (iii) des pertes résistives. Afin de réaliser des mini-modules à hauts rendements, une architecture alternative a été étudiée et comparée à la structure conventionnelle. Dans cette structure, les grilles métalliques utilisées pour le contact avant du dispositif servent également à connecter de manière monolithique les cellules adjacentes. Ces travaux ont permis de prouver de manière théorique et expérimentale que cette architecture permettait d’obtenir des résultats bien plus intéressants que le design standard. Un des avantages mis en évidence est la réduction de l’épaisseur de la couche fenêtre permettant ainsi la diminution des pertes optiques et résistives. Seulement, une différence subsiste : le module présente une tension de circuit ouvert plus faible que la cellule photovoltaïque. Cette différence peut être due à la croissance de l’absorbeur de Cu(In,Ga)Se2 sur verre qui est découvert lors de la gravure P1. Celle-ci engendrerait des propriétés de CIGSe différentes tant au niveau de sa morphologie, de sa composition que de sa structure cristalline. Enfin, les meilleurs résultats obtenus montrent un rendement de 17,2% pour le module alternatif (avec un facteur de forme de 81%), contre 16,4% (avec un facteur de forme de 75%) pour la cellule. Ce résultat prometteur ouvre de nouvelles voies pour réduire l'écart observé entre les cellules en laboratoire et les modules industriels.One of the main drawbacks to industrially develop the CIGSe thin-film solar cells in the photovoltaic market is the lack of technological maturity, since the CIGSe lab-scale conversion efficiency has never been higher (23.3%). In this thesis, we address the key problem of the performance gap between the cells and the modules. These losses are due to the monolithic interconnection (carried out using the standard engravings P1, P2 and P3) which induces (i) a reduction of the active surface of the panels, (ii) optical losses as well as (iii) resistive losses. In order to create high-efficiency minimodules, an alternative architecture has been studied and compared to the conventional structure. In this structure, the metal grids, normally used for the front contact, are also used to monolithically connect the adjacent cells. Our work confirms experimentally and theoretically that these alternative modules lead to better photovoltaic performances that the modules with the standard design. One of the advantages highlighted in this thesis, is the reduction of the window layer thickness which enables to further decrease the optical and resistive losses. The only remaining difference between the photovoltaic cell and the module is the lower open circuit voltage of the module. This difference may be due to the fact that a part of the CIGSe layer grows on glass which is uncovered during the P1 etching. This leads to a different CIGSe morphology, composition and crystal structure. Finally, our results show a 17.2% best lab-scale conversion efficiency for the alternative module (with a fill factor of 81%), against 16.4% for the cells (with a fill factor of 75%). These very promising results open new horizons and ways to further improve the observed performance gap between the solar cells made at the laboratory and the industrial modules
Préparation et caractérisation de couches minces de CIGS déposées par différentes techniques
No full textTechnologies les plus prometteuses pour suivre le défi de la production d'énergie. La première partie de cette mémoire aborde les absorbeurs de CISe préparés par co-évaporation (3 étapes) et l'effet de l'oxygène (ainsi que le sodium) dans les absorbeurs et des cellules solaires. La température du substrat de 1ère étape la plus élevé (400°C), conduit à un rendement maximal de 12% (Voc=460mV, Jsc=37mA/cm2, FF=78,3%). L’oxydation des couches précurseurs de In2Se3 a montré que les oxydations prolongées ont donnée lieu à faibles rendements de cellules solaires. Les cellules de CISe sans Na ont été fortement dégradées après l’oxydation, avec une baisse de Voc (-72%) et de FF (- 45%). La deuxième partie de la mémoire traite avec la croissance des couches de CISe par un procédé hybride (pulvérisation pyrolyse suivie par coévaporation). La croissance est basée sur un processus de co-évaporation en 3 étapes, mais en remplaçant la couche de 1ère étape avec un couche In2Se3 pyrolysée. Il a été montré qu’une couche de CISe de haute qualité peut être obtenue. L’optimisation des conditions de croissance du procédé hybride (régime du Cu) a permis des dispositifs avec un rendement de 11,1%. Une amélioration peut être atteinte par la diminution de la recombinaison au niveau du contact arrière.In photovoltaics, the thin film Cu(In,Ga)Se2 (CIGSe) technology is one of the most promising technology to keep up with today’s energy production challenge. The first part of this work address the CISe absorbers films prepared by the 3-stage co-evaporation process. Also, the effect of the oxygen (along with sodium) in the CISe absorbers and solar cells is investigated. The highest 1st-stage substrate temperature (400 C) leads to the highest efficiency of 12% (Voc=460mV, Jsc=37 mA/cm2, FF=78.3%). Oxidation of the In2Se3 precursors films showed that long time exposures resulted in low solar cell parameters. The CISe cells without sodium are degraded after oxidation, with a drop in Voc (-72%) and FF (-45%). The second part of the work deals with the growth of CISe films by a hybrid process which involves two deposition techniques, namely spray pyrolysis and co-evaporation. The process is based on a 3-stage coevaporation process but replacing the 1st-stage film with an In2Se3 spray pyrolyzed film. It was shown that highquality CISe films can be obtained. Optimization of the hybrid process growth conditions (Cu regime) allowed solar cells with efficiencies of 11.1% (Voc=438mV, Jsc=37 mA/cm2, FF=67.5%). Further improvement could be achieved by the decrease of recombination at the back contact
Elaboration and characterization of CuGaSe₂ / c-Si tandem solar cells : toward a monolithic two-terminals approach
No full textPour dépasser la barre théorique de 30% de rendement de conversion, les cellules solaires en tandem basées sur des sous cellules en silicium cristallin (c-Si) sont l'une des architectures les plus prometteuses. En outre, une approche monolithique à deux terminaux utilisant des couches minces à grand gap comme cellule supérieure ne nécessiterait pas de modification significative des modules solaires existants. L’absorbeur Cu(In,Ga)(S,Se)₂ (CIGS) est un candidat prometteur grâce à sa haute efficacité (le record de rendement en module est d'environ 19%) et à son énergie de bande interdite accordable. De plus, on peut noter que des cellules solaires CIGS sont déjà produites à l’échelle industrielle. La chalcopyrite pure-gallium et pure-sélénium CuGaSe₂ (CGSe) peut également être utilisée comme absorbeur de cellule supérieure dans un dispositif multijonction grâce à sa valeur optimale de bande interdite (1,68 eV). Néanmoins, le rendement de conversion actuel des cellules solaires à base de CGSe est encore faible (11,9%) et son intégration tandem n’améliorerait pas, en l’état, les performances de la cellule c-Si. L'objectif de cette thèse est d'optimiser l’élaboration d'une cellule solaire mono-jonction à base de CGSe, de développer un processus de dépôt de cellule supérieure sans dégradation ni contamination de la cellule inférieure en c-Si et enfin d'élaborer des cellules photovoltaïques tandem CGSe / c-Si fonctionnelles.To overcome 30% conversion efficiency, tandem solar cells based on crystalline silicon (c-Si) sub-cells are one of the most promising architecture regarding the theoretical predictions. Furthermore, a monolithic two-terminal approach using wide bandgap thin films as top cell does not require significant modification of the existing solar modules. Cu(In,Ga)(S,Se)₂ absorber layer is a promising candidate thanks to its high efficiency (the module record efficiency is around 19%) and to its tunable bandgap energy. In addition, industrial solar cells are currently produced from this material. In-free CuGaSe₂ (CGSe) can also be used as top cell absorber in a multi-junction device thanks to its optimal bandgap value (1.68eV). Nevertheless, the actual conversion efficiency of CGSe based solar cells is still low (11.9%). The objective of this thesis is to optimize the development of a single-junction solar cell based on CGSe, to develop top cell deposition process without degradation nor contamination of the c-Si bottom cell and finally to elaborate functional CGSe / c-Si tandem solar cells
Modelling of electrochemical storage and photovoltaic production in an autonomous solar drone
No full textCette thèse porte sur l’étude d’un système de gestion de l’énergie d’un drone alimenté par l’énergie solaire et de batteries de stockage au travers du développement d’un simulateur énergétique modélisant son comportement. L’étude se porte sur un drone solaire à aile tandem, ce dernier est équipé de quatre ailes dont les surfaces sont recouvertes par des panneaux solaires composés de cellules de types couches minces en arséniure de gallium (III-V). De plus, deux packs batteries lithium-ion embarqués dans le drone assurent une bonne autonomie en vol. La méthodologie du design du simulateur est basée sur l’interface entre des modèles équivalents électriques et mathématiques afin d’évaluer la quantité d’illumination sur les ailes, la production photovoltaïque et la charge et décharge des batteries. Une attention particulière a été apportée à la mesure sur les éléments constituant le drone solaire dans le processus de modélisation. Ces mesures ont permis d’extraire des paramètres équivalents afin d’alimenter le simulateur. Ce simulateur permet de prédire la puissance solaire effective produite par les panneaux solaires et la tension des batteries pendant le vol du drone. Les paramètres du vol tels que l’irradiance, les angles d’inclinaison du soleil et les angles d’Euler du drone ont été intégrés comme données d’entrée du simulateur. Une validation de celui-ci est assurée grâce au comparatif avec un vol réel effectué par le drone. Une étude paramétrique est également menée présentant l’effet des conditions climatiques et géographiques sur la durée de vol du drone.This thesis deals with a drone supplied by solar energy through the development of an energy simulator modelling its behavior during flight. The study focuses on a tandem wings UAV, the latter is equipped by four wings for which their respective surface areas are covered by solar panels based thin film gallium arsenide photovoltaic cells (III-V). Moreover, the drone is embedded with two lithium-ion battery packs to achieve a good flight duration. The design methodology for this work is built around the interface between electrical equivalent and mathematical models to evaluate the irradiance fraction on the wings, the photovoltaic production and the charge/discharge of the batteries. An extensive study was performed on the measurements of the energetic systems in the modeling process This data allowed the extraction of the equivalent parameters of the models improving the simulator. This simulator allows the prediction of effective photovoltaic power produced by the solar panels and the battery voltage during the drone flight. Flight parameters such as irradiance, Sun inclination angle and drone Euler angles have been considered as input parameters of the simulator and reported as function of the flight time. A validation process is performed with a comparison between a real flight operated by the UAV and the same simulated flight. Moreover, a parametric study is presented in order to evaluate the effect of both the climatic and geographical conditions on the flight duration
Data of Micromechanics-based material networks revisited from the interaction viewpoint; robust and efficient implementation for multi-phase composites
No full textData related to the publication (we would be grateful if you could cite the paper in the case in which you are using the data)
title = "Micromechanics-based material networks revisited from the interaction viewpoint; robust and efficient implementation for multi-phase composites",
journal = "European Journal of Mechanics - A/Solids",
year = "2022",
volume = "91",
pages = " 104384 ",
doi = "https://doi.org/10.1016/j.euromechsol.2021.104384",
author = "Nguyen, Van Dung and Noels, Ludovic"Van Dung Nguyen is a Postdoctoral Researcher at the Belgian National Fund for Scientific Research (FNRS
Ludovic-Mohamed Zahed’s Universal Performance of French Citizenship and Muslim Brotherhood
No full textIn this chapter, I present the life and work of Ludovic-Mohamed Zahed, who is the founder of three non-profit associations over the past several years: Les Enfants du Sida (2006), Homosexuels musulmans de France (HM2F) (2010), and Musulman-es Progressistes de France (2012). He is also the author of Révoltes extraordinaires: un enfant du sida autour du monde (2011) and Le Coran et La Chair (2012), and co-author of Queer Muslim Marriage (2013). During the last few years, the French media have covered his same-sex marriage in Cape Town to husband Qiyaam Jantjies-Zahed in 2011, the publication of his book, Le Coran et La Chair in 2012, as well as and his creation of La Mosquée inclusive de l’Unicité, the first “gay friendly” or inclusive mosque in Paris, in 2012.</p
Signatures de la compétition des transitions polaire et distortive du titanate de strontium
No full textMONTPELLIER-BU Sciences (341722106) / SudocTOULON-BU Centrale (830622101) / SudocSudocFranceF
Les defis du developpement local au Senegal
No full textThis book is an uncompromising analysis of Senegal's decentralisation policy in rural areas. It discusses the state's inability to promote local development, despite this being its main raison d'?tre in a context of poverty. To identify reasons for the shortcomings, the author goes beyond policy statements and explores, sociologically, the compatibility of the behaviour and the cultural context of actors with the pursuance of local development objectives. Yet, there are indeed solutions to the actors' lethargy and to the weak coverage of the initiatives undertaken. The solutions can be found in the methodical and civic mobilisation around more ambitious actions that are more adapted to receptive localities, though opened to modernity and perfectly anchored in the culture for positive results. Rosnert Ludovic Alissoutin holds a PhD in Law. Since 1995, he has been working as a consultant on development issues in Senegal and Africa, particularly local development issues. The particularity of his approach lies in the rejection of scientific exclusivism and recourse to a multi disciplinary, open and flexible analysis of the complexity of human development. It is this perspective that informed his doctoral thesis on La Gestion de l'eau en milieu aride, which discusses legal, anthropological, geographical, and sociological issues. For additional information on his profile and work, visit his website: http://www.ralissoutin.com
Les Amérindiens wayana et la mise en place du projet de Parc national guyanais
No full textThis article sums up the history of the project for a National Park in French Guiana and examines some of the most recent attempts to resolve the Amerindian territorial issue. Insofar as conservationist practice in Amazonia is founded on the premise that the Amerindians share the same heritage-preserving relationship to nature, the article reviews the animist foundations of these relationships. Furthermore Wayana society has already undergone major socioeconomic changes, which the author has attempted to relate to those likely to arise when the new national park is established.Cet article récapitule l'historique du projet de Parc national du sud de la Guyane et s'attarde sur quelques unes des tentatives les plus récentes pour résoudre la question territoriale amérindienne. Dans la mesure où la pratique conservationniste en Amazonie s'appuie sur le postulat que les Amérindiens partageraient avec elle un même rapport patrimonial à la nature, les fondements animistes de ces rapports sont réexaminés. La société wayana étant traversée par de nombreux bouleversements socio-économiques, certains d'entre eux sont ensuite reliés à ceux que l'on peut attendre de la mise en place future du parc.Leprêtre Ludovic. Les Amérindiens wayana et la mise en place du projet de Parc national guyanais. In: Journal d'agriculture traditionnelle et de botanique appliquée, 40ᵉ année, bulletin n°1-2,1998. Conserver, gérer la biodiversité : quelle stratégie pour la Guyane ? sous la direction de Marie Fleury et Odile Poncy. pp. 559-576
Data and Software of "Development of a Geometric Modeling Strategy for the Generation of Representative Unit Cells in 2D Braids"
No full text<h1><strong>Id: Data of following publication</strong></h1>
<p>title = "Development of a Geometric Modeling Strategy for the Generation of Representative Unit Cells in 2D Braids",<br>journal = "",<br>pages = "",<br>year = "",<br>issn = "",<br>doi = "",<br>author = "José Rothkegel, Benjamin Renson, Michael Bruyneel, Ludovic Noels"</p>
<p>Data doi on 10.5281/zenodo.10829042</p>
<h1>pyRVE</h1>
<h2><a href="#python-code-for-geometrical-generator-for-braided-composites-rve"></a><em>Python Code for Geometrical Generator for Braided Composites RVE</em></h2>
<p>pyRVE is a code written in <em>Python</em> using the <em>GMSH API</em> that generates the Representative Unit Cell (RUC) of braided composites. It allows the generation of the RUC of triaxial braided for <em>Diamond</em> and <em>Regular</em> patterns.</p>
<h2><a href="#requirements"></a>Requirements</h2>
<p>To run, it requires:</p>
<ul>
<li>The GMSH Python API, which must be built with OpenCascade support.
<ul>
<li>Choose a local installation directory; <code>CMAKE_INSTALL_PREFIX=HOME/local/gmsh</code>, and <code>GMSHPY_INSTALL_DIRECTORY=HOME/local/gmsh</code> e.g.;</li>
<li>Make that directory part of your <code>export PYTHONPATH=PYTHONPATH</code>.</li>
<li>After compiling use <code>make install</code>.</li>
</ul>
</li>
<li>The CM3 app dG3D if the final RVE homogenized solution is needed (<a href="https://gitlab.onelab.info/cm3/cm3Libraries">https://gitlab.onelab.info/cm3/cm3Libraries</a>).</li>
<li>Make sure that the latest version of OpenCascade (OCCT) is used. Current used version in occt-V7.8.0.</li>
</ul>
<h2><a href="#usage"></a>Usage</h2>
<h3><a href="#file-structure"></a>File Structure</h3>
<p>A typical run case must have a file structure, where:</p>
<ul>
<li><code>brd</code>: the files <code>.brd</code> and <code>.brep</code> are located here. The <code>.brd</code> is a backup of the <code>braidClass</code> instance used in the model saved using <code>pickle</code>, the <code>.brep</code> is the Boundary Representation file that can be opened with <em>GMSH</em>.</li>
<li><code>csv</code>: the <code>.csv</code> file saved here is the initial output of the code. It contains the actually used dimensions and the final cover factor of the braid.</li>
<li><code>data</code>: It contains <code>.csv</code> files with the material properties and the dimensions of the tows. The original model dimensions are read from here.</li>
<li><code>dir</code>: In the case of running the RVE homogenization, the directions of the tow fibers are stored here. They are saved for post processing.</li>
<li><code>msh</code>: the mesh file <code>.msh</code> obtained after the geometry geneartion is stores here.</li>
<li><code>png</code>: in the case of automatic post processing, png files are stored here.</li>
<li><code>res</code>: this folder is used to store the homogenization results. They have to be moved here.</li>
<li><code>stp</code>: if acitvated, a <code>.stp</code> file of the geometry is stored here</li>
<li><code>svg</code>: the projection of the geometry on the <em>x-y</em> plane is stored here.</li>
<li><code>vtk</code>: A copy of the mesh file without the matrix mesh is sotred here as a `.vtk`` file.</li>
</ul>
<h3><a href="#how-to-run"></a>How to Run</h3>
<p>We will consider the current file structure to run the example in 000_Base. To run the code, it can be called from the command prompt as</p>
<div>
<pre><code>python3 ../../source/mainRVE.py --name <i> --pattern <pattern></code></pre>
</div>
<p>In this case, the <code>--name</code> refers to the index that will be given to the model, where <code><i></code> must be changed to an integer and <code>--pattern</code> refers to the wanted pattern to be used, where <code><pattern></code> must be changed to either <code>dia</code> or <code>reg</code>.</p>
<blockquote>
<p>Note: <code><code>--name</code>cat</code> can also be used to reproduce the regular pattern benchmark of the paper. In that case, the volume fraction of fiber in the tows is hard coded as the provided value in the reference (i.e. 0.86). For other cases, the volume fraction is evaluated from the tow cross-sections.</p>
<p>Note: <code>mainRVE.py</code> must be accesible from the directory where the case is being run. This example shows the usage of the current file structure.</p>
</blockquote>
<h3><a href="#all-command-line-options"></a>All Command Line Options</h3>
<p>The code can be run using further options that serve different purpouses, some serving pre processing needs and other serving run administration. The different command line options are:</p>
<ul>
<li>Required:
<ul>
<li><code>--name</code> : it gives a suffix to the run model. It is usually an integer.</li>
<li><code>--pattern</code> : indicates the type of pattern to be used to build the geometry. The two current options are <code>dia</code> for diamond and <code>reg</code> for regular.</li>
</ul>
</li>
<li>Optional
<ul>
<li><code>-dG3D</code>: it indicates that the homogenization of the generated RUC is to be perfomed.</li>
<li><code>-GMSH</code> : it indicates that GMSH must be open upon competion of the generation of the mesh.</li>
<li><code>-loadModel</code> : it will try to load a premade model. It will ignore <code>--pattern</code>.</li>
<li><code>--rndPrm</code> : it will generate randomized geometrical parameters. It can be used to generate batches of results. It takes an argument that can be <code>2</code>, <code>4</code> or <code>6</code>. Currently, <code>2</code> gives a random value for <code>s_axial</code> and <code>theta</code>, <code>4</code> randomizes the same as <code>2</code> and adds <code>h_axial</code> and <code>h_bias</code>, and <code>6</code> randomizes the same as <code>4</code> and adds <code>w_axial</code> and <code>w_bias</code>.</li>
</ul>
</li>
<li>Pre-Processing
<ul>
<li><code>-refCF</code>: it tells the code to generate a grid of values for <code>s_axial</code> and <code>theta</code> where only the cover factor is obtained. It is meant for posterior graphing purposes.</li>
</ul>
</li>
</ul>
<h3><a href="#examples"></a>Examples</h3>
<p>Following the run options, a few examples are indicated</p>
<ul>
<li>A basic mesh generation run for the basic data, considering a <strong>regular pattern</strong>, for a model named <strong>2</strong>:</li>
</ul>
<div>
<pre><code>python3 ../../source/mainRVE.py --name 2 --pattern reg</code></pre>
</div>
<ul>
<li>The generation of the cover factor data and export, considering a <strong>regular pattern</strong>:</li>
</ul>
<div>
<pre><code>python3 ../../source/mainRVE.py --pattern reg -refCF</code></pre>
</div>
<ul>
<li>A run for the modified basic data, where the <strong>2</strong> parameters are modified <em>randomly</em>, considering a <strong>regular pattern</strong>, for a model named <strong>2</strong>:</li>
</ul>
<div>
<pre><code>python3 ../../source/mainRVE.py --name 2 --pattern reg --rndPrm 2</code></pre>
</div>
<ul>
<li>A run, where model <strong>2</strong> already exists in <code>brd</code> folder but not the <code>.msh</code> and <code>.vtk</code> files:</li>
</ul>
<div>
<pre><code>python3 ../../source/mainRVE.py --name 2 -loadModel </code></pre>
</div>
<h2><a href="#code-structure"></a>Code Structure</h2>
<p>The code is implemented into Python files, where <code>mainRVE.py</code> runs the whole code. The files are:</p>
<ul>
<li>Braid:
<ul>
<li><code>braidClass.py</code> :</li>
<li><code>bzrPairClass.py</code> :</li>
</ul>
</li>
<li>Geometry
<ul>
<li><code>bezrClass.py</code> :</li>
<li><code>bilnClass.py</code> :</li>
<li><code>patchClass.py</code> :</li>
<li><code>pntSetClass.py</code> :</li>
<li><code>pointClass.py</code> :</li>
<li><code>sctnClass.py</code> :</li>
<li><code>stripeClass.py</code> :</li>
<li><code>surfClass.py</code> :</li>
<li><code>surfOffClass.py</code> :</li>
</ul>
</li>
<li>Material:
<ul>
<li><code>chamis.py</code> :</li>
</ul>
</li>
<li>Tools:
<ul>
<li><code>dataIO.py</code> :</li>
<li><code>postDirection.py</code> :</li>
<li><code>tool.py</code> :</li>
<li><code>toolData.py</code> :</li>
</ul>
</li>
<li><code>curveClass.py</code> :*</li>
</ul>
<p> </p>
<p> </p>
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