Dissertations / Theses on the topic 'Chiffrement à bas coût'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 48 dissertations / theses for your research on the topic 'Chiffrement à bas coût.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Coggia, Daniel. "Techniques de cryptanalyse dédiées au chiffrement à bas coût." Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS217.
Full textThis thesis contributes to the cryptanalysis effort needed to trust symmetric-key primitives like block-ciphers or pseudorandom generators. In particular, it studies a family of distinguishers based on subspace trails against SPN ciphers. This thesis also provides methods for modeling frequent cryptanalysis problems into MILP (Mixed-Integer Linear Programming) problems to allow cryptographers to benefit from the existence of very efficient MILP solvers. Finally, it presents techniques to analyze algebraic properties of symmetric-key primitives which could be useful to mount cube attacks
Duval, Sébastien. "Constructions pour la cryptographie à bas coût." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS078.
Full textThis thesis explores the construction of symmetric cryptography primitives. We reach better constructions than that of the literature, we a focus on the reduction of implementation costs. We study three types of primitives: block ciphers, which are the most commonly used in symmetric cryptography, a stream cipher designed for a specific application and a message authentication algorithm. We reduce the costs of the two main components of block ciphers: S-boxes and diffusion matrices. Feistel and MISTY-like structures appear to be a good choice to design secure S-boxes at a low cost, and lead us to new S-boxes with the best known trade-off between security and implementation cost. We also study the Butterfly structure which yields S-boxes with an excellent security. As for diffusion matrices, we develop an algorithm to look for formal matrices in a polynomial ring, then we instantiate its outputs to obtain matrices which are optimal in terms of diffusion at a lower cost than those of the literature. We also identify a weakness in the stream cipher FLIP, designed to fit some very specific cost constraints. We show that FLIP requires a different analysis than other stream ciphers and deduce from it an attack, which led to an update in FLIP to get a more resilient cipher. Finally, we study MAC algorithms, which are used to authenticate messages. Combining works from the literature, we build a MAC which is less costly than those used in practice with an equivalent security, aiming at an implementation on 32-bit micro-controllers
Huynh, Le-Phuc. "Analyse et conception d’algorithmes de chiffrement légers." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0223.
Full textThe work presented in this thesis has been completed as part of the FUI PACLDIO project, whose aim is to provide new security protocols and algorithms for the Internet of Things, and more specifically wireless sensor networks. As a result, this thesis investigates so-called lightweight authenticated encryption algorithms, which are designed to fit into the limited resources of constrained environments.The first main contribution focuses on the design of a lightweight cipher called Lilliput-AE, which is based on the extended generalized Feistel network (EGFN) structure and was submitted to the Lightweight Cryptography (LWC) standardization project initiated by NIST (National Institute of Standards and Technology).Another part of the work concerns theoretical attacks against existing solutions, including some candidates of the NIST LWC standardization process. Therefore, some specific analyses of the Skinny and Spook algorithms are presented, along with a more general study of boomerang attacks against ciphers following a Feistel construction
Lallemand, Virginie. "Cryptanalyse de chiffrements symétriques." Electronic Thesis or Diss., Paris 6, 2016. http://www.theses.fr/2016PA066657.
Full textThe main subject of this thesis is the security analysis of symmetric key ciphers. Specifically, we study several recently proposed block and stream ciphers and prove that the level of security stated by their designers is overestimated. The ciphers we study were all designed in order to meet the needs of one of the new applications of symmetric cryptography, which include symmetric ciphers for very constrained environments.The first part of the thesis is dedicated to the analysis of block ciphers with techniques based on differential cryptanalysis. We start with the description of a truncated differential attack on the family of lightweight ciphers KLEIN. Next, we analyse two ciphers that were designed in such a way that they could be easily and effectively protected against side-channel attacks: Zorro and Picaro. We show that the design choices made by their designers lead to weak diffusion properties. We exploit these imperfections to devise a differential cryptanalysis of Zorro and a related key attack on Picaro.The second part of this thesis deals with stream ciphers and gives an analysis of two innovative designs: Sprout and Flip. Sprout was designed in order to limit its hardware area size and to suit very constrained environments, while Flip reaches efficient performances when used in FHE schemes. In both cases, we find flaws that lead to attacks of the particular set of parameters proposed for these ciphers
Lallemand, Virginie. "Cryptanalyse de chiffrements symétriques." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066657/document.
Full textThe main subject of this thesis is the security analysis of symmetric key ciphers. Specifically, we study several recently proposed block and stream ciphers and prove that the level of security stated by their designers is overestimated. The ciphers we study were all designed in order to meet the needs of one of the new applications of symmetric cryptography, which include symmetric ciphers for very constrained environments.The first part of the thesis is dedicated to the analysis of block ciphers with techniques based on differential cryptanalysis. We start with the description of a truncated differential attack on the family of lightweight ciphers KLEIN. Next, we analyse two ciphers that were designed in such a way that they could be easily and effectively protected against side-channel attacks: Zorro and Picaro. We show that the design choices made by their designers lead to weak diffusion properties. We exploit these imperfections to devise a differential cryptanalysis of Zorro and a related key attack on Picaro.The second part of this thesis deals with stream ciphers and gives an analysis of two innovative designs: Sprout and Flip. Sprout was designed in order to limit its hardware area size and to suit very constrained environments, while Flip reaches efficient performances when used in FHE schemes. In both cases, we find flaws that lead to attacks of the particular set of parameters proposed for these ciphers
Schrottenloher, André. "Quantum Algorithms for Cryptanalysis and Quantum-safe Symmetric Cryptography." Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS271.
Full textModern cryptography relies on the notion of computational security. The level of security given by a cryptosystem is expressed as an amount of computational resources required to break it. The goal of cryptanalysis is to find attacks, that is, algorithms with lower complexities than the conjectural bounds.With the advent of quantum computing devices, these levels of security have to be updated to take a whole new notion of algorithms into account. At the same time, cryptography is becoming widely used in small devices (smart cards, sensors), with new cost constraints.In this thesis, we study the security of secret-key cryptosystems against quantum adversaries.We first build new quantum algorithms for k-list (k-XOR or k-SUM) problems, by composing exhaustive search procedures. Next, we present dedicated cryptanalysis results, starting with a new quantum cryptanalysis tool, the offline Simon's algorithm. We describe new attacks against the lightweight algorithms Spook and Gimli and we perform the first quantum security analysis of the standard cipher AES.Finally, we specify Saturnin, a family of lightweight cryptosystems oriented towards post-quantum security. Thanks to a very similar structure, its security relies largely on the analysis of AES
Bouhamri, Zine-Abidine. "Transmission multi-standards sur lien optique bas-coût." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00957588.
Full textCoisel, Iwen. "Authentification et Anonymat à Bas-coût : Modélisations et Protocoles." Caen, 2009. http://www.theses.fr/2009CAEN2041.
Full textIn our daily life, security of many applications are based on cryptographic mechanisms. In some of them, privacy issues are a major concern. For example in internet context, a user expects the service provider not to divulgate his identity. In this thesis, I first give a formal definition of zero-knowledge proofs of knowledge (ZKPK), very useful for designing digital signatures. I prove the security of a generic construction of proofs of knowledge of discrete logarithm relations set. Then, I present state of the art of different signature schemes ensuring users' anonymity. Afterwards I adapt these protocols to the cooperative set-up, in which an intermediary helps the user perform some computations during the protocol. I also define a formal security model which is robust against corruption of the intermediary, while improving protocol efficiency. In the second part of this thesis, I present the security requirements for RFID tags authentication protocols. As these small embedded devices are potentially integrated into many various products, they must be intraceable so that nobody can trace their holder. As anonymity does not provide this property on its own, it must be included in the security model. Finally, I describe two authentication protocols which provide this security level. The first one uses a secret key infrastructure and a key update mechanism. The other one uses a public key infrastructure and an encryption algorithm
Lefranc, David. "Authentification asymétrique à bas coût et vérification assistée par ordinateur." Caen, 2005. http://www.theses.fr/2005CAEN2024.
Full textPassault, Grégoire. "Optimisation de la locomotion de robots bas coût à pattes." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0297/document.
Full textA promise of legged robots is being able walking on irregular or uneven floor. It is already used nowadays in education and entertainment applications. We introduce the Metabot platform, an open-source quadruped robot developped for education. This takes place in current technological context which allows, thanks to an access to fast prototyping and off-shelf components, building legged robots that were formerly only present in laboratories. This platform was used for teaching in secondary schools, allowing students to discover robotics, and especially programming. We then describe an environment designed to study legged robots locomotion, extending the expert controller designed for Metabot. We realized some physics simulation experiments and analyzed it to get a better understanding of the legged locomotion underlying rules. At last, we get a closer look at biped locomotion, for which stability problems arise. When developping our Sigmaban platform, a small-sized humanoid robot created to participate in RoboCup soccer, we designed foot pressure sensors that allow us to estimate the robot center of pressure. We exploit these sensors to improve the lateral stability on the robot, creating a closed-loop walk
Merzouk, Khalil. "ÉTUDE D'UN SYSTÈME BAS COÛT DE TRANSMISSION OPTIQUE PAR MULTIPLEXAGE TEMPOREL." Phd thesis, Grenoble INPG, 2008. http://tel.archives-ouvertes.fr/tel-00348066.
Full textMekki, Sami. "Architecture et traitement numérique pour les communications UWB à bas coût." Paris, ENST, 2009. http://www.theses.fr/2009ENST0069.
Full textThis thesis report deals with a low cost IR-UWB receiver for high-data rates (100Mbps). The system under consideration uses a PPM modulation with a simple analog energy detector. In ordeer to overcome the problems inherent to high-data rates, such as inter-symbol interference and intra-symbol interference, a probabilistic equalizer is proposed. On this study, we define a well matched energy model that takes advantage from the interference levels. COmputer simulations are performed on the channel models of IEEE 802. 15. 3a Task Group. Numerical results show that the energy equalizer improve the receiver performances if perfect CSI was assumed. Channel parameters necessary for equalization are estimated by the mean of the EM algorithm. The energy equalizer and the EM algorithm are jointly run into the loop of an iterative channel decoder in order to enhance the BER performance and achieve 100Mbps data rate. We show that the EM algorithm is capable of estimating the channel parameters as accurately as the perfect CSI. Besides, a new training sequence for channel estimation is proposed. This allows to obtain a very low complexity channel estimation with regards to the EM algorithm. Finally, the hardware implementation feasability of the probabilistic equalizer is studied. For this purpose, we apporximate and replace certain complex mathematical functions, such as the chi-squared likelihood function, by ones less complex. Then, the computational complexity is further reduced by performing the calculations in the logarithmic domain. Fixed-point data types simulations are carried out and compared to the results obtained from the reference floating point non-approximated functions
Sion, Charles. "Réalisation d’une caméra infrarouge à bas coût pour application grand public." Thesis, Lille 1, 2011. http://www.theses.fr/2011LIL10094/document.
Full textThe thermal radiation emitted by human body can be detected in the 8-14 µm range by an infra-red sensor. Cameras imagined from this type of detectors were initially reserved for army personal usage but the market is in a large growth due to commercial applications like thermography or human detection. Thermal detectors microbolometers are the most spread technologies with 95% of the market but some others are showing interesting results as thermoelectrical arrays. This document explains the realisation of an infrared camera that can be used for human detection using a technology developed in the group. Contrary to the bolometric matrices based on a variation of electrical resistance, this sensor working by thermoelectric effect does not require power supply and the associated electronic interface is very simple. A special attention was related to the reduction in the manufacturing costs by decreasing the size of the thermoelectric pixels and using a polyethylene Fresnel lens in order to use this type of system in the individual housing. Series of 5x5, 7x7, 10x10 pixels microsensors were modelled and realized during this thesis as well as a complete imaging device using of 7x7 pixels array. The mathematical model developed during this work shows that a further increase in length reduction is possible if more pixels are needed
Theillet, Gérald. "Développement d'un support microfluidique papier pour le diagnostic bas coût d'arboviroses émergentes." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0725/document.
Full textThe incidence of arboviruses infections has increased dramatically in recent decades in tropical and sub-tropical areas worldwide. Dengue and chikungunya viruses are typically transmitted by mosquitoes and can cause a wide range of symptoms, and sometimes death. Although conventional diagnostic tests can provide diagnosis of acute infections, access to these tests is often limited in developing countries. Early and prompt diagnosis is crucial to improve patient management. Consequently, there is an urgent need to develop affordable, simple, rapid, and robust tools that can be used at ‘Point of Care’ settings.We developed and evaluated a PAD for the detection of the dengue Non Structural 1 (NS1) viral protein in blood and plasma samples. The PAD was able to detect specifically 10 ng.mL-1 of NS1 protein in various sample types and in 6-8 minutes. Secondly, an improved version of the PAD obtained by laser cutting was designed and tested for the detection of dengue NS1 protein and virus-specific IgM in blood and plasma. Each parameter could be detected in 8 minutes. PAD development performed on dengue fever was then applied to the detection of chikungunya virus IgM in human sera, using viral Pseudo-Particles (PPs). These synthetic antigens have proven to be powerful tools for specific IgM detection. The results obtained showed a sensitivity of 70.6% and a specificity of approximately 98% with a time to results of less than 10 minutes. The PAD showed few cross reactions with other arbovirusess. The PPS were finally characterized with different physico-chemical methods in order to determine the key factors of their performances
Calenzo, Patrick. "Développement de nouvelles architectures mémoires non volatiles bas coût et basse consommation." Aix-Marseille 1, 2009. http://www.theses.fr/2009AIX11051.
Full textThe objectives of this thesis are to conceive and to develop non volatile memories with floating gate which are low cost, low voltage consumption and compatible with a CMOS standard logic process. In order to be carried out, a state of the art has put forth the cells which are “high-achieving” in this technology. This has permitted to see the qualities and the defects of the cells and enabled to target the main points which need careful consideration. From this onwards, a calibration methodology, usable for any semi conductor device, has been developed. This methodology was put into practice on an EEPROM cell, which served as the foundations for the development of the memory cells, throughout this paper. Furthermore, a single poly silicon double implant memory cell has been studied. This cell has been developed from its operating concept to its electric validation on silicon. The manufacturing process suggested gave way to a single poly-silicon memory cell in a CMOS logic technology. In addition, the cell consumption is in perfect accordance with the low voltage consumption criteria. Finally, this cell is interesting in regards to its size which is only 1,1 μm² in a technology of 0,13 μm. This makes it the smallest existing cell for this particular type of memory. In parallel to this work, another single poly silicon cell, which exists in two different versions, has been suggested. These cells have the particularity to be created in a shallow trench isolation. This reinforces the idea of low cost because the surface of the unit cell can be reduced but at the same time remains compatible with a CMOS standard logic process. All the basics needed to create this cell have been validated electrically and give way to encouraging energy consumption results. The outlook for this work would be to improve the two developed concepts in order to have them industrialized
Rabobason, Yvon Georges. "Modélisation de système antennaire flexible à bas coût pour objets communicants non planaire." Rouen, 2016. http://www.theses.fr/2016ROUES060.
Full textFlexible electronics is currently considered as one of the technological solutions to face up to geometric constraints, lower cost and technological requirements. This emergence will ultimately drive the market for connected clothing, implanted electronics (in-body electronics). However, the flexible technology is not mature and has some issues that remain to lift as the choice of substrates both effective, environmentally friendly and at lower costs, modeling (analytic or digital) of a system or flexible subsystem, or the analysis of electromagnetic phenomena related to non-planar geometry. This manuscript presents the memory of my PhD thesis that focuses on the modeling of flexible antenna system for low-cost non-planar communicating objects. First, the different parameters such as the quality factor, antenna efficiencies, gain or bias, for evaluating the performance of an antenna are introduced. Subsequently, research work on flexible substrate based different antenna structures is presented. The main characteristics of flexible plastic substrates commonly used are addressed. The choice towards the substrates Kapton HN, as the best compromise cost-effectiveness robustness is justified. The influence of the antenna curvature constitutes the main object of the present PhD thesis. In this way, the study on the EM phenomena associated with the use of a flexible patch antenna structure is developed. Novel analytical formulas for assessing the antenna radiation efficiency in discrete curvatures scenarios are established. In addition, a methodology providing an analysis and modeling approach to passive and active 1×2 antenna arrays is presented and validated. Finally, two new structures of flexible high performance antennas in terms of bandwidth and radiation efficiencies are designed and implemented. The Kapton-based broadband structures are based on slots antenna topology with new matching adaptation technique by the use of lumped elements. The influence of the curvature on the slot antenna prototypes are analyzed and discussed
Yao, Thierry. "Modélisation et conception d'une mémoire non-volatile dédiée aux applications bas coût télé-alimentées." Paris, ENST, 2002. http://www.theses.fr/2002ENST0018.
Full textGardes, Cyrine. "Un salariat à bas coût. Le travail dans une enseigne low-cost de bricolage." Thesis, Paris, EHESS, 2019. http://www.theses.fr/2019EHES0076.
Full textThe current crisis of purchasing power, a very pressing problematic at the present time, contributed to the rise and success of low-price retail in various sectors of the economy (food, hardware retail, rail and train transportation), self-promoted as « low-cost » and described as a major commercial innovation, with its low margins, reduced assortment and services, and generally its low production costs. This business model, never before studied in sociology, is the object of the present work, which purpose is to illustrate the different forms taken by exploitation and capitalism, and their effect on the workforce, in a context of economical crisis. The analysis angles itself mainly on work, and was nourished by an ethnographic study in two stores and warehouses of a low-cost hardware retail chain business, that we will call « Bricostock ». We show that the activity of these « low-cost » hardware retail stores, which has similarities with other production models, is characterized by simultaneously managing a very high flow of goods with an accelerated stock rotation, and a fast customer flow, whose interactions with the salespeople therefore have to be reduced. The workers' multi-tasking activities allow an important reduction in workforce numbers, compared to the other businesses of the sector. We also show that this type of organization is based on the work of individuals with specific social characteristics : management and subaltern workers alike are more socially vulnerable than in other firms and have to accept work conditions. Lastly, from the perspective of doing a sociology of the work group's structuration, we study different configurations of the group's social relations. Peer groups, despite the work and employment conditions that could keep them from existing, are present, and they are structured by various principles of division and cohesion. We will show in which situations work peer groups seem relevant to the actors or might be made redundant by other situations : for exemple, if men are dominant in the organisation and in the work group (men make up 83 % of the sales workforce in the firm we studied, one of the highest rate in the sector of hardware retail), there are gender-mixed sociabilities based on the workers' seniority, on age, on a shared position or on common adversaries, such as management and customers. This study deals with the dynamics of reproduction or transformation of social relations in low-cost retail and with the diffuse forms of conflictuality in this type of organisation
Carcanague, Sébastien. "Algorithme de positionnement précis en environnement contraint basé sur un récepteur bas-coût GPS/GLONASS." Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2013. http://tel.archives-ouvertes.fr/tel-00951914.
Full textPorcher, Willy. "Conception, mise en oeuvre et optimisation d'électrodes composites à bas coût pour accumulateurs Li-ion." Nantes, 2008. http://www.theses.fr/2008NANT2080.
Full textThis work is focused on the development of LiFePO4-based positive composite electrodes of 3mAh. Cm-2 through the aqueous processing route. The viability of the aqueous route for LiFePO4 was initially evaluated with a study on its stability in water. The results show, in particular, that a protective layer of Li3PO4 of some nanometers is formed at the grains surface but without any degradation of the electrochemical performances. However, to limit the capacity loss associated with the aqueous processing, this study shows that the immersion time should be limited, the solid loading of the LiFePO4 aqueous suspension should be high, and that the natural pH should not be modified. The formulations that were developed contain a combination of water soluble polymers which satisfies three functions: the one of dispersing and stabilizing agent of the LiFePO4 and carbon black powders, the one of giving proper rheological properties to the electrode ink with respect to the tape casting process, and the one of binder to confer a satisfactory adhesion and cohesion to the electrode. Additives with various molecular structure and therefore specific properties are tested, independently, according to the function sought by their introduction. A fourth original additive was also introduced, an amino-functional synthetic polyelectrolyte, with the aim to tailor a self-assembly between the LiFePO4 active material and the carbon black electronic conductor. The electrodes of 3mAh. Cm-2 obtained are perfectly easy to handle, and their electrochemical performances are superior than those classically obtained with the N-methyl-2-pyrrolidone route, with a higher active material concentration
Nguyen, Viet Huong. "Développement d'électrodes transparentes par méthodes de dépôt à pression atmosphérique et bas coût pour applications photovoltaïques." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI072/document.
Full textThe thesis work involves the study of Indium-free Transparent Conductive Materials (TCMs), key components of many optoelectronic devices, using Atmospheric Pressure Spatial Atomic Layer Deposition (AP-SALD). This new approach shares the main advantages of conventional ALD but allows open-air, very fast deposition of high-quality nanometer-thick materials over large surfaces. We focused on the optimization of the electrical properties of Aluminum doped Zinc Oxide (ZnO:Al) films, one of the most studied Transparent Conductive Oxides (TCOs). The effect of several experimental parameters on the physical properties of the deposited films has been evaluated. The carrier transport mechanism at grain boundaries was identified to be tunneling rather than thermionic emission in highly doped ZnO, thanks to a new model we have developed using the Airy Function Transfer Matrix Method. Accordingly, the electron trap density at grain boundaries for ZnO:Al samples (2.2×1020 cm-3) prepared by AP-SALD was estimated to be about 7.6×1013 cm-2. Our model shows that grain boundary scattering is the dominant scattering mechanism in our films. We found that UV assisted annealing (~ 200 °C) under vacuum was an efficient method to reduce grain boundary traps, resulting in an improvement of mobility from 1 cm2V-1s-1 to 24 cm2V-1s-1 for ZnO and to 6 cm2V-1s-1 for ZnO:Al. We have also used AP-SALD to fabricate high-performance, stable and flexible TCMs based on metallic nanowire network. For that, we developed composite electrodes by coating silver/copper nanowires (AgNWs/CuNWs) with ZnO, Al2O3, or ZnO:Al. A thin conformal coating deposited by AP-SALD technique enhanced drastically the thermal/electrical stability of the AgNWs/CuNWs network. High optoelectronic properties (resistivity ~ 10-4 Ωcm, transmittance ~ 90 %) of the AgNW/ZnO:Al composite make them very appropriate for application as TCM, especially for flexible devices.Finally, as a soft deposition technique, AP-SALD is completely compatible to the Silicon heterojunction (Si-HET) solar cell technology in terms of interface passivation. The integration of ZnO:Al and AgNWs based TCMs to Si-HET cell has also been explored
Liu, Chao. "Dimensionnements et comparaisons de convertisseurs électromécaniques à bas coût et à grande disponibilité pour véhicules électriques." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC049/document.
Full textToday, the concerns of the energy crisis and the reduction of gas emissions stimulate the research in several electric vehicle domains. As the cost of rare earth magnetic materials has increased significantly in recent years, electrical motors without permanent magnets draw more attention, such as induction motors, wound-synchronous motors, switched reluctance motors, and synchronous reluctant motors. In this thesis, induction and synchronous reluctant machines are chosen to be studied for the electric vehicle traction application since they are low costly and fed up with similar power electronics and control strategies.Nonlinear analytical models of induction and synchronous reluctant machines are established and validated. Besides, economical and mechanical models are developed as well. Based on established analytical models, the geometry and the control parameters of these studied machines are calculated to define the total energy losses during the driving cycle. A bi-objective optimization is carried out to minimize total energy losses and motor costs. At last, the optimized machines are compared from their electric, energetic and economic performances, with the help of the Pareto Fronts obtained
Jacquemoud-Collet, Fanny. "Etiquette RFID bas coût sur support papier : Optimisation du procédé industriel innovant / intégration d’une fonctionnalité capteur." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20194.
Full textThe RFID, for Radio Frequency Identification, has grown considerably in recent years become an essential mode of traceability and identification. Market players are numerous and among them, Tageos (Montpellier, France) established since 2008 an innovative process for manufacturing the RFID tag on paper, economic and ecologic. However, even if the performances obtained during a previous work (Thesis C. Ramade 2008-2011) were sufficient to allow mass production, they are not optimal in particular with respect to the established results in laboratory. It is in this context that ranks this work which is always carried out in close collaboration between the Institute of Electronics of South and TAGEOS company S.A.S. Our efforts were focused : on process optimization of realization of RFID antenna working on the analysis, methods or protocols and technical resources on the preparation of the paper substrate, on alternative and complementary solutions to realize RFID antenna and RFID chip bonding and on the reliability and quality of finished products. Moreover, in this work we have also demonstrated the valorization of our low cost RFID tag by integrating a sensor functionality. The industrial process of producing of this tag taking accounts of TAGEOS process
Jacquemoud-Collet, Fanny. "Etiquette RFID bas coût sur support papier : optimisation du procédé industriel innovant / intégration d’une fonctionnalité capteur." Electronic Thesis or Diss., Montpellier 2, 2014. http://www.theses.fr/2014MON20194.
Full textThe RFID, for Radio Frequency Identification, has grown considerably in recent years become an essential mode of traceability and identification. Market players are numerous and among them, Tageos (Montpellier, France) established since 2008 an innovative process for manufacturing the RFID tag on paper, economic and ecologic. However, even if the performances obtained during a previous work (Thesis C. Ramade 2008-2011) were sufficient to allow mass production, they are not optimal in particular with respect to the established results in laboratory. It is in this context that ranks this work which is always carried out in close collaboration between the Institute of Electronics of South and TAGEOS company S.A.S. Our efforts were focused : on process optimization of realization of RFID antenna working on the analysis, methods or protocols and technical resources on the preparation of the paper substrate, on alternative and complementary solutions to realize RFID antenna and RFID chip bonding and on the reliability and quality of finished products. Moreover, in this work we have also demonstrated the valorization of our low cost RFID tag by integrating a sensor functionality. The industrial process of producing of this tag taking accounts of TAGEOS process
Nassar, Maxime. "Contre-mesures à bas coût contre les attaques physiques sur algorithmes cryptographiques implémentés sur FPGA Altera." Phd thesis, Télécom ParisTech, 2012. http://pastel.archives-ouvertes.fr/pastel-00790669.
Full textNassar, Maxime. "Contre-mesures à bas coût contre les attaques physiques sur algorithmes cryptographiques implémentés sur FPGA Altera." Electronic Thesis or Diss., Paris, ENST, 2012. http://www.theses.fr/2012ENST0010.
Full textSide-Channel Analysis (SCA) and Fault Attacks (FA) are techniques to recover sensitive information in cryptographic systems by exploiting unintentional physical leakage, such as the power consumption. This thesis has two main goals: to draw a review of the state of the art of FPGA-compatible countermeasures against SCA and implement t the selected ones with the minimum area and performances overhead. Symmetrical algorithms, specially AES, are studied and several vulnerabilities of usual protections, namely Dual-rail with Precharge Logic (DPL) and masking are analysed, as well as the issue of performance and area overheads. In this context, three new countermeasures are considered: 1. Balance placement and routing (PAR) strategies aiming at enhancing existing DPLs robustness when implemented in modern FPGAs. 2. A new type of DPL called Balanced Cell-based Dual-railLogic (BCDL), to thwart most of the known DPL weaknesses. BCDL also possess a fault resilience mechanism and provides implementation optimisations on FPGA, achieving competitive performances and area overhead. 3. The Rotating S-Box Masking (RSM), a new masking technique for the AES that shows high leveles of robustness and performances while bringing a significant reduction of the area overhead. Finally, several new SCAs are presented and evaluated. Firstly the “Rank Corrector” a SCA enhancement algorithm. Secondly, The FPCA, introduces a novel SCA distinguisher based on the PCA. Then, combinations of either acquisition methods or SCA distinguishers are discussed and show significant decrease in the number of measurements required to perform a successful attack
Quoizola, Sébastien. "Epitaxie en phase vapeur de silicium sur silicium mésoporeux pour report sur substrats économiques et application photovoltai͏̈que bas coût." Lyon, INSA, 2003. http://theses.insa-lyon.fr/publication/2003ISAL0078/these.pdf.
Full textThin film solar cells by layer transfer process is a very promising way to reduce material cost in photovoltaïc industry. The aim of this study is to transfer thin silicon layers (50 µm) on cheap substrate. In order to warranty a highly conversion efficiency, monocrystalline silicon is required. Thin monocrystalline silicon film is grown on mesoporous silicon by vapor phase epitaxy. The porous silicon layer presents a double porosity structure and acts as both a seeding layer and a sacrificial layer. During hydrogen high temperature annealing, pores are coarsened in the low porosity layer and enlarged in the high porosity layer. These structural modifications allow the growth of the epitaxial silicon layer and its separation from the silicon substrate. As obtained thin silicon film serves as the active layer in an one side solar cell with interdigited contacts. Substrate can be then re-used for a novel thin silicon film
Esteve, Aurore. "Isolement de biomarqueurs cellulaires et moléculaires en oncologie et développement d'approches bas-coût pour leur analyse en routine clinique." Thesis, Toulouse, INSA, 2018. http://www.theses.fr/2018ISAT0048.
Full textThe objective of this work has been to develop novel micro-devices for the isolation of circulating tumor cells as well as exploring different techniques to facilitate analysis of CTCs at the cellular and molecular level in clinical routine. A first innovative approach of in vivo CTC capture exploiting their specific physical traits was considered. Placing the capture micro-device directly within the bloodstream could allow the screening of a bigger volume of blood and thus provide a higher and more representative number of CTCs to analyze. Different techniques aiming to spread the use of liquid biopsy in clinical routine by simplifying and decreasing the cost of analysis were explored. Among these techniques, directed capillary assembly conceived to stretch and immobilize 1D biomolecules enabled the isolation of free circulating DNA fragments from whole blood samples. In the context of precision medicine, another approach may be to test the efficacy of drugs on CTCs isolated from the patient himself so as to personalize the treatment. In this perspective, we integrated the capture micro-devices into a platform allowing in situ culture of trapped cells in vitro. To recreate an environment conductive to their proliferation, the structuration of cellulosic biocompatible materials was investigated. Our results provide a set of technologies that could contribute to the democratization of liquid biopsy in clinical routine
Araujo, Viana Carlos. "Développement technologique et intégration système de VCSEL et HPT SiGe pour des applications radio-sur-fibre 60 GHz bas coût." Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1003/document.
Full textWireless communication technologies have become one of the most popular and indispensable part of people's lives in the recent years, offering mobility and services never before available from mobile communication until local network communication. This work is based on the frame of the French ORIGIN project and intended to explore the Home Area Network using the most recent Wi-Fi standard at 60 GHz with the goal to present a solution for the upcoming days where MultiGbit/s wireless communication will be required. The ORIGIN solution is characterized by the complementary action of two technologies: 60 GHz Wireless communication and Radio-over-Fiber (RoF) infrastructure. The project pretends to propose a real prototype based on RoF transducers and a Multipoint-to-Multipoint architecture to cover the entire house. This thesis covers from the single optoelectronic chip devices until the system implementation and the final demonstrator. The light source and the photodetector choice were very important since it dictated the RoF transducer architecture. Our choice was on 850 nm multimode devices (GaAs VCSEL and SiGe HPT) which allow relaxed constraints on the optical packaging and, therefore, low cost solutions. In terms of performances those devices are limited in a few tens of Gigahertz of bandwidth which was the reason for the intermediate frequency (IF) architecture. This thesis work addressed the electrical and optical interconnection of the optoelectronic chip devices. It explored the integration of hybrid amplification stages and passive networks within optoelectronic receivers and emitters. The optical packaging issues were addressed through a conventional coupling technique using a ball lens first. The die device performances were evaluated and compared with a packaged module in terms of frequency response, noise and nonlinearities. Since performances are usually measured as link performances we proposed a definition of the Opto-microwave figures of merit, such as Opto-microwave gain, noise, nonlinearities and EVM. They are presented and integrated into behavioral models, allowing both the individual performances extraction and system design. The integration of the RoF module in the system is the final part of this thesis. The performances were measured and simulated at each integration step. The final demonstrator based on the multipoint-to-multipoint architecture was implemented using an optoelectronic central node for the signal repartition and the Green Box for signal controlling. Real-time bidirectional transmission between two commercial WirelessHD devices at ~3 Gbit/s was validated. In a final section directions to improve VCSEL and SiGe HPT are explored. 25 GHz analogue VCSELs are explored with a focus on their dimensions, improved access and the potential of a suited matching approach. A novel collective and passive optical coupling technology is also proposed for both VCSEL and top illuminated detectors that couple smaller and faster devices
El-Huni, Walid. "Modélisation de cellules solaires multi-tandem bas coût et très haut rendement à base de nitrures des éléments III-V." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS296/document.
Full textNitrides of III-V elements, have been widely studied because of their interessting applications in the LED light-emitting diodes, laser diodes and photodetectors. The bandgap of such ternary or quaternary alloys can be adjusted depending on the composition, at photon energies ranging from infrared to ultraviolet. This adjustable direct bandgap over a wide range, making these materials valuable for photovoltaic applications due to the possibility of inventing not only multi-junction solar cells at high efficiency, but also third generation solar cells such as cells with intermediate bandgap, based solely on nitrides alloys. In addition to their large adjustable bandgap, nitrides also show other interesting photovoltaic properties, such as low effective masses of the charge carriers, high mobility, high absorption coefficient and a radiation tolerance. The technology of III-V nitrides has demonstrated its ability to grow high quality crystal structures and to manufacture optoelectronic devices, which confirm its potential for photovoltaic solar energy with very high efficiency. By incorporating this material with crystalline silicon junction, we can have a multijunction cell with very high efficiency with a competitive cost
Dias, Ferreira João Marcelo. "Silicium multicristallin de type N pour la fabrication de cellules solaires à bas coût et à rendement de conversion élevée." Aix-Marseille 3, 2010. http://www.theses.fr/2010AIX30069.
Full textDelaine, Florentin. "Étalonnage in situ de l'instrumentation bas coût pour la mesure de grandeurs ambiantes : méthode d'évaluation des algorithmes et diagnostic des dérives." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX075.
Full textIn various fields going from agriculture to public health, ambient quantities have to be monitored in indoors or outdoors areas. For example, temperature, air pollutants, water pollutants, noise and so on have to be tracked. To better understand these various phenomena, an increase of the density of measuring instruments is currently necessary. For instance, this would help to analyse the effective exposure of people to nuisances such as air pollutants.The massive deployment of sensors in the environment is made possible by the decreasing costs of measuring systems, mainly using sensitive elements based on micro or nano technologies. The drawback of this type of instrumentation is a low quality of measurement, consequently lowering the confidence in produced data and/or a drastic increase of the instrumentation costs due to necessary recalibration procedures or periodical replacement of sensors.There are multiple algorithms in the literature offering the possibility to perform the calibration of measuring instruments while leaving them deployed in the field, called in situ calibration techniques.The objective of this thesis is to contribute to the research effort on the improvement of data quality for low-cost measuring instruments through their in situ calibration.In particular, we aim at 1) facilitating the identification of existing in situ calibration strategies applicable to a sensor network depending on its properties and the characteristics of its instruments; 2) helping to choose the most suitable algorithm depending on the sensor network and its context of deployment; 3) improving the efficiency of in situ calibration strategies through the diagnosis of instruments that have drifted in a sensor network.Three main contributions are made in this work. First, a unified terminology is proposed to classify the existing works on in situ calibration. The review carried out based on this taxonomy showed there are numerous contributions on the subject, covering a wide variety of cases. Nevertheless, the classification of the existing works in terms of performances was difficult as there is no reference case study for the evaluation of these algorithms.Therefore in a second step, a framework for the simulation of sensors networks is introduced. It is aimed at evaluating in situ calibration algorithms. A detailed case study is provided across the evaluation of in situ calibration algorithms for blind static sensor networks. An analysis of the influence of the parameters and of the metrics used to derive the results is also carried out. As the results are case specific, and as most of the algorithms recalibrate instruments without evaluating first if they actually need it, an identification tool enabling to determine the instruments that are actually faulty in terms of drift would be valuable.Consequently, the third contribution of this thesis is a diagnosis algorithm targeting drift faults in sensor networks without making any assumption on the kind of sensor network at stake. Based on the concept of rendez-vous, the algorithm allows to identify faulty instruments as long as one instrument at least can be assumed as non-faulty in the sensor network. Across the investigation of the results of a case study, we propose several means to reduce false results and guidelines to adjust the parameters of the algorithm. Finally, we show that the proposed diagnosis approach, combined with a simple calibration technique, enables to improve the quality of the measurement results. Thus, the diagnosis algorithm opens new perspectives on in situ calibration
Vogt-Schilb, Adrien. "Éléments sur la transition vers du capital bas carbone." Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC1114/document.
Full textThis thesis shows that while greenhouse gases are a stock pollution that imposes a shadow carbon cost that increases over time, it may be socially desirable to invest now in the deployment of expensive emission-reduction measures. This results solely from taking into account inertia inherent to the accumulation of low-carbon capital, in the absence of any other market imperfection. This thesis also covers the choice of policy instruments that imperfect governments can use to ensure the market implement these investments. It suggests that if governments cannot commit credibly to a carbon price path, or cannot fully compensate the losers from the introduction of a carbon price, then sector-scale policy instruments that incentivize investment in clean capital may be more effective and more acceptable than the carbon price
Devigne, Louise. "Solutions robotiques bas coût pour l’aide à la navigation en fauteuil roulant électrique : vers une contribution dans le champ de la rééducation neurologique." Thesis, Rennes, INSA, 2018. http://www.theses.fr/2018ISAR0024/document.
Full textWhile the use of a wheelchair allows people with disabilities to compensate for a loss of mobility, people with severe disabilities are denied the use of a power wheelchair. Indeed, cognitive or visual perception impairments can affect the ability to drive safely. In this context, access to mobility can be improved by providing appropriate assistive technologies to compensate for loss of mobility in all types of environments. While the first research on smart wheelchairs dates back to the early 1980s, no solutions have yet been proposed on the market or in rehabilitation centers and other specialized structures. This work aims to propose a set of solutions for power wheelchair navigation assistance designed in close collaboration with users and therapists. The development of such assistive solutions faces multiple robotic challenges combining innovative detection techniques, shared control with the user. In this work, a driving simulator supporting research and development of new robotic solutions for wheelchair navigation assistance is proposed. Then low-cost semi-autonomous assistance solutions for navigation assistance in indoor and outdoor environments are detailed. The evaluation with able-bodied participants allows to validate the mathematical methods and provide proof of concept of the proposed solutions. Finally, the first clinical evaluations with regular users at Pôle MPR Saint Hélier show the validation of the proposed framework in terms of user satisfaction
Thévenard, Julian. "Contribution à la conception à bas coût d'antennes 3D reconfigurables : solutions originales d'intégration en technologie plastique pour les systèmes sans fil du futur." Brest, 2008. http://www.theses.fr/2008BRES2011.
Full textThis thesis is dedicated to the design of 3D smart antennas for forthcoming wireless devices. Our research work has been motivated by the actual wireless trends leading to service concentration within WLAN and device miniaturisation. Thus, antenna design is nowadays guided by size constraints and their capacity to deal with fading interference, wireless environments while improving the performances of devices in terms of communication quality, power consumption. This thesis presents a multi-sector antenna solution associating many Vivaldi-antennas to provide a solution for the targeted application which is an embedded system constituting of high definition wireless cameras. A theoretical analysis of the Vivaldi antenna is first performed and then a novel concept of multi-sector antenna has been introduced and validated. Then, in order to target consumer market and to reduce the manufacturing costs in high volume production, the metallized molded plastic technology which enables molding 3D complex structures has been retained. An original without-welding transfer system has been developed for integrating the antenna to the rest of the system. The characterization of a prototype has resulted in the validation of the use of plastics for such applications. This antenna has been integrated in a wireless camera ; a protective radome having as additional property to improve the overall performances of the device is finally designed. This simplified integration procedure associated to a monitoring of the performances and the flexibility of the system makes it a good candidate for various applications like domestic WLAN, mesh networks or for MIMO technology
Picard, Charles-Florian. "Développement de méthodes et d’outils associant la modélisation numérique et des mesures in situ afin de concilier la qualité de l’air intérieur et l’efficacité énergétique." Thesis, La Rochelle, 2019. http://www.theses.fr/2019LAROS014.
Full textIndoor Air Quality (IAQ) knowledge is necessary to address the sanitary and socio-economic issues of this field, in both public and private domains. Laboratory-grade measuring devices are generally burdensome and expensive. Alone, they cannot provide a full response to large-scale IAQ information needs. This work focuses on the use of two alternative methods in this context, which are IAQ modeling and the use of low-cost sensors, with the purpose of removing certain barriers to their deployment. As a first step, this manuscript describes the numerical developments made in order to enrich a library of models for nodal modeling of IAQ, initiated by EDF R&D. The main additions include the modeling of humidity and indoor particle deposition. In order to evaluate the relevance of the choices made, a validation work has been carried out by confronting the IAQ library results with analytical solutions, experimental data and other modeling tools. One of the major issues of this type of modeling method is the complex choice of input data. This step can have a significant impact on the results provided and there is a need to assess their influence. The modeling of various mono-zone or multi-zone case studies, from the residential and tertiary sectors, has highlighted the advantages and the limitations of the developed tool regarding the quality of the predictions of the concentrations of gaseous and particulate pollutants. A sensitivity analysis was carried out to identify the key parameters responsible for model uncertainty in a few configurations. As a second step, an innovative method of particulate matter measurement has been developed, associating several low-cost particle sensors. This approach allowed to tackle the issues of reliability of this kind of sensors and the limitations of their detection capabilities. The design of prototypes and their use in different indoor environments have given promising results. Several developments are then proposed in order to generalize and validate the robustness of this approach
Barrami, Fatima. "Low-complexity direct-detection optical OFDM systems for high data rate communications." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT057/document.
Full textA possible approach to maximize the data rate per wavelength, is to employ the high spectral efficiency discrete multitone (DMT) modulation. The work presented in this thesis mainly focuses on optimizing the power consumption and cost of DMT, that are the major obstacles to its market development. Within this context, we have first developed novel techniques permitting to discard the use of Hermitian symmetry in DMT modulations, thus significantly reducing the power consumption and the system cost. We have next proposed an asymmetric linear companding algorithm permitting to reduce the optical power of conventional DCO-OFDM modulation with a moderate complexity. A new VCSEL behavioural model based on the use of the VCSEL quasi-static characteristic was also developed to accurately evaluate the VCSEL impact on DMT modulations. Finally, we have built an experimental system to experimentally validate our proposed techniques. Several simulations and measurement results are then provided
Masure, Loïc. "Towards a better comprehension of deep learning for side-channel analysis." Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS443.
Full textThe recent improvements in deep learning (DL) have reshaped the state of the art of side-channel attacks (SCA) in the field of embedded security. Yet, their ``black-box'' aspect nowadays prevents the identification of the vulnerabilities exploited by such adversaries. Likewise, it is hard to conclude from the outcomes of these attacks about the security level of the target device. All those reasons have made the SCA community skeptical about the interest of such attack techniques in terms of security evaluation. This thesis proposes to draw a better understanding of deep learning for SCA. We show how the training of such estimators can be analyzed through the security evaluation prism, in order to estimate a priori the complexity of an SCA, without necessarily mounting the attack. We also remark on simulated experiments that those models, trained without prior knowledge about the counter-measures added to protect the target device, can reach the theoretical security bounds expected by the literature. This validates the relevance or not of some counter-measures such as secret-sharing or hiding, against DL-based SCA. Furthermore, we explain how to exploit a trained neural network to efficiently characterize the information leakage in the observed traces, even in presence of counter-measures making other classical charactertization techniques totally inefficient. This enables a better understanding of the leakage implicitly exploited by the neural network, and allows to refine the evaluator's diagnosis, in order to propose corrections to the developer
Vafaei, Raha. "Design, fabrication and characterization of a VMOS monolithic integrated optical detector." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENT120/document.
Full textThe work presented in this PhD manuscript deals with the monolithic integrationof an optical galvanic isolation unit within the vertical FET structure of a 600Vpower transistor. The optical galvanic isolation unit is a photodetector that is responsiblefor transferring the gating information signal from an external control unit to the powerswitch. The necessary energy to switch the power device is provided by means of a TIAfollowed by a gate driver. This document has four chapters: introduction and motivation:Integrated glavanic isolation for power devices, Compatible integrated phootdiodes (IPDs)for power switches: Modeling and design, IPD fabrication and characterization, and conclusionsand future work. The results of this research work are interesting for a wide rangeof applications specially as the power electronic community strives for a fully integratedpower function with lower implementation costs and reliable, high level galvanic isolationsolutions that are compact and cost effective
Harmouch, Khaled. "Conception et réalisation d’un moteur piézoélectrique pour application automobile haute température." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC007.
Full textThe goal of this thesis is to designand build a piezoelectric motor for an exhaustgas heat recovery application. This applicationrequires relatively high torque, highcompactness, thermal endurance and acceptablecost.In order to achieve this goal, the design of theengine passes by the choice of its mode ofoperation. This choice is made based on criteriasuch as low cost, high torque and compactness.After the determination of the architecture ofthe piezoelectric motor, the modelling isaddressed. The purpose of the model is tocompute the torque/speed characteristicsknowing the motor dimensions and materials,the surface state of the contact, the precompressionforce and the supply voltage.The modeling developed was validated byexperimental measurements.In the last part, the motor is build and tested. Itsdynamic behavior and torque/speedcharacteristics were measured. With theexception of the peak and blocking torque, allthe performances required by the applicationwere fulfilled.Finally, the model results are compared to themeasurements done on the prototype. Thedynamic behavior is well predicted by themodel. However, the model is not able tocompute accurately the stator displacements.This implies inaccuracy in the motorcharacteristics computation. It turns out thatthey are related to the absence of the coefficientof contact damping
Hayes, Maxim. "Intégration de collecteurs de charges avancés dans les cellules solaires bifaciales à haut rendement : vers un procédé générique pour les nouveaux matériaux silicium." Electronic Thesis or Diss., Aix-Marseille, 2020. http://www.theses.fr/2020AIXM0519.
Full textThanks to a relatively simple fabrication process and high conversion efficiency values the PERC structure is well established at the industrial level. Nevertheless, industrial PERC solar cells performances are mostly limited by two charge carrier recombination sources: P thermally diffused emitter on the front side and the Al-Si interfaces at the rear contacts. The main goal of this work aims at limiting both recombination sources. A selective emitter (SE) obtained by plasma immersion ion implantation (PIII) is developed for an integration on the front side; whereas a B-doped polysilicon (poly-Si) on oxide passivated contact (PC) is integrated on the back side. The second goal of this work consists in evaluating the compatibility between these advanced carrier collectors and directionally solidified Si materials. SE featuring good geometrical properties and a well-controlled doping were fabricated thanks to an in situ localized doping process obtained with a specific mask developed for PIII. Besides, several metal deposition technologies were investigated for the poly-Si(B). Fire-through screen-printing appears as the most promising approach so far. Indeed, the deposition of a non-sacrificial hydrogen-rich layer allowed to reach an excellent surface passivation level for solar cell precursors. However, the specific contact resistivity obtained remains too high for an optimal cell integration. Lastly, the fabrication of poly-Si PC showed excellent external gettering efficiencies for multicrystalline Si. Thus, the potential of the developed cell structure to be integrated with low-cost and low carbon footprint materials is encouraging
Hamdi, Maher. "Conception de tags d'identification sans puce dans le domaineTHz." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENT048/document.
Full textThis thesis work deals with the development of a new generation of low-cost Chipless tags operating in the THz frequency domain, it has been supported by the french national agency for research (ANR-09-VERS-013 « THID » ). It covers a wide area of applications such as the identification and/or unitary authentication of commercial items, identity papers, access control…To manufacture these tags, we proposed to use a periodic stack of dielectric material layers with different refractive index and whose thickness is of the order of the wavelength, commonly known as a one dimensional photonic crystal. The electromagnetic signature of such a structure exhibits photonic bandgaps (PBG), i.e. frequency windows in which light propagation is prohibited. We suggested modifying the periodicity of the crystal to create defect levels (peaks) for example in the 1st PBG to encode binary information. This particular structure allows to precisely tuned an electromagnetic signature. To ensure a mass and cost effective industrialization, we retained basic materials which are widely used in the pulp and paper industry: paper and polyethylene. The choice of these materials, which must combine high index contrast and low absorption, represents the first and a crucial step in this work. We characterize a wide range of materials using classical THz time domain spectroscopy (THz-TDS) and we propose two families of tags based on paper and polyethylene. Furthermore, we developed two methods to encode binary information, both based on the absence or presence of peaks in a PBG, peaks whose number and position depend on the introduced defects of periodicity. In a real identification test, a coding capacity of nearly 20-bit has been demonstrated. We also showed that the information contained in the electromagnetic response of these THz tags can be used for other applications related to the unitary authentication and by using the correlation coefficient as criterion for discrimination of the different signatures. Therefore, we evaluate the performance of an authentication test based on this criterion in various analysis domains: time, frequency and time-frequency. We showed that a study of the spectrogram (combining time and frequency representation) is much more relevant than a study in the only time or frequency domain
Atchuthan, Dinesh. "Towards new sensing capabilities for legged locomotion using real-time state estimation with low-cost IMUs." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30316/document.
Full textEstimation in robotics is an important subject affected by trade-offs between some major critera from which we can cite the computation time and the accuracy. The importance of these two criteria are application-dependent. If the computation time is not important for off-line methods, it becomes critical when the application has to run on real-time. Similarly, accuracy requirements are dependant on the applications. EKF estimators are widely used to satisfy real-time constraints while achieving acceptable accuracies. One sensor widely used in trajectory estimation problems remains the inertial measurement units (IMUs) providing data at a high rate. The main contribution of this thesis is a clear presentation of the preintegration theory yielding in a better use IMUs. We apply this method for estimation problems in both pedestrian and humanoid robots navigation to show that real-time estimation using a low- cost IMU is possible with smoothing methods while formulating the problems with a factor graph. We also investigate the calibration of the IMUs as it is a critical part of those sensors. All the development made during this thesis was thought with a visual-inertial SLAM background as a mid-term perspective. Firthermore, this work tries to rise another question when it comes to legged robots. In opposition to their usual architecture, could we use multiple low- cost IMUs on the robot to get valuable information about the motion being executed?
Rodriguez, Delphy. "Caractérisation de la pollution urbaine en Île-de-France par une synergie de mesures de surface et de modélisation fine échelle." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS341.
Full textThe harmful effects of air pollution need a high-resolution concentration estimate. Ambient pollutant concentrations are routinely measured by surface monitoring sites of local agencies (AIRPARIF in Paris area, France). Such networks are not dense enough to represent the strong horizontal gradients of pollutant concentrations over urban areas. And, high-resolution models that simulate 3D pollutant concentration fields have a large spatial coverage but suffer from uncertainties. Those both information sources exploited independently are not able to accurately assess an individual’s exposure. We suggest two approaches to solve this problem : (1) direct pollution measurement by using low cost mobile sensors and reference instruments. A high variability across pollution levels is shown between microenvironments and also in the same room. Mobile sensors should be deployed on a large scale due to their technical constraints. Reference instruments are very expensive, cumbersome, and can only be used occasionally. (2) by combining concentration fields of the Parallel Micro-SWIFT-SPRAY (PMSS) model over Paris at a horizontal resolution of 3 meters with AIRPARIF local ground stations measurements. We determined “representativeness areas” - perimeter where concentrations are very close to the one of the station location – only from PMSS simulations. Next, we developed a Bayesian model to extend the stations measurements within these areas
Pelati, Daniel. "Elaboration of GaAs solar cells based on textured substrates on glass." Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS456.pdf.
Full textThe increasing demand for clean energy has driven research toward higher efficiency and lower cost solar cells. Gallium arsenide solar cells detain the record efficiency for single junction devices but the high cost of the substrate limits their applications. In this work, we investigate an alternative GaAs substrate based on a low cost silica support coated by a thin (20 nm) Germanium layer. This layer is nearly lattice-matched to GaAs and can be crystallized with a high (111) texture using Metal Induced Crystallization (MIC). However, this requires a careful optimization of the deposition and annealing parameters. Here, we use a specially designed in situ optical microscope to optimize the annealing sequence. In particular, we identified two crystallization pathways, of which one should be minimized to obtain a good (111) crystalline texture. We then perform the heteroepitaxy of GaAs on this Ge seed layer using Molecular Beam Epitaxy, keeping the initial (111) crystal texture. We identify specific growth conditions for the twin- and defect-free growth of GaAs on Ge(111) surfaces. We also observe the growth of GaAs adopting the (111)A polarity on Ge (111) rather than the expected (111)B orientation. Finally, we fabricate (111)-oriented GaAs solar cells with 15,9% efficiency on a monocrystalline GaAs(111)B substrate. The transfer to standard Ge(111) monocrystalline wafers and to our Ge-coated silica pseudo-substrates reveals doping issues related to the (111)A orientation of the GaAs, as well as surface roughening due to grain boundaries in the initial Ge seed layer
Faye, Papa Latyr. "Le potentiel d'offres de vols à bas prix au Québec." Thèse, 2020. http://depot-e.uqtr.ca/id/eprint/9413/1/eprint9413.pdf.
Full textBéchevet, Delphine. "Contribution au développement de tag RFID UHF et Microondes sur matériaux plastiques." Phd thesis, 2005. http://tel.archives-ouvertes.fr/tel-00119837.
Full textRouger, Nicolas. "Intégration monolithique des fonctions d'interface au sein de composants de puissance à structure verticale." Phd thesis, 2008. http://tel.archives-ouvertes.fr/tel-00344847.
Full textd'applications de ces travaux couvrent un large spectre, favorisant l'émergence de convertisseurs de puissance innovants, à haute densité de puissance et coût de fabrication réduit.