Dissertationen zum Thema „K-Systèmes“
Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an
Machen Sie sich mit Top-50 Dissertationen für die Forschung zum Thema "K-Systèmes" bekannt.
Neben jedem Werk im Literaturverzeichnis ist die Option "Zur Bibliographie hinzufügen" verfügbar. Nutzen Sie sie, wird Ihre bibliographische Angabe des gewählten Werkes nach der nötigen Zitierweise (APA, MLA, Harvard, Chicago, Vancouver usw.) automatisch gestaltet.
Sie können auch den vollen Text der wissenschaftlichen Publikation im PDF-Format herunterladen und eine Online-Annotation der Arbeit lesen, wenn die relevanten Parameter in den Metadaten verfügbar sind.
Sehen Sie die Dissertationen für verschiedene Spezialgebieten durch und erstellen Sie Ihre Bibliographie auf korrekte Weise.
Bai, Xiao. „Traitement personnalisé de requête top-K : des systèmes centralisés aux systèmes décentralisés“. Phd thesis, INSA de Rennes, 2010. http://tel.archives-ouvertes.fr/tel-00545642.
Der volle Inhalt der QuellePigot, Claude. „Étude de systèmes dibaryoniques étranges dans les réactions K⁻ + d → K⁺ + X⁻, K⁻ + d → π ⁻ + X⁺ et π ⁺ + d → K⁺ + X⁺ entre 0,9 et 1,4 GeV/c“. Paris 11, 1987. http://www.theses.fr/1987PA112158.
Der volle Inhalt der QuelleThis thesis presents the results of the analysis of the experiment "Dibaryon" (PS159), performed at CERN. This experiment studies the strange dibaryonic systems in the reactions K- + d →K+ + X-, K- + d →π- + X+ et π+ + d → K+ + X+ between. 9 and 1. 4 GeV/c. A dibaryon, with strangeness -2, is searched for in the reaction K- + d → K+ + X-. An upper limit for the production cross section of such a state is established in the range 5 to 40 nb/sr, for a dibaryon mass between 2100 to 2500 MeV/c2. A signal in the mass spectrum of the x+ system, at 2129 MeV/c2, already indicated in the reaction K- + d →π- + X+, is observed in the reaction π+ + d →K + X+. A study of this signal is performed in these two channels at different energies. The triangular diagram model, with an intermediary sigma exchanged, is in good agreement with the variation of the production cross section in the two channels and as a function of the energy
Martinez, Aguilera Servet. „Description ergodique des processus de Markov qui convergent vers l'équilibre associés aux k-systèmes“. Paris 6, 1986. http://www.theses.fr/1986PA066242.
Der volle Inhalt der QuelleMaachi, Belaid. „Influence du potassium sur les propriétés morphologiques, structurales et catalytiques de phases submicroniques des systèmes Fe - K - O et Fe - Al - K - O : application à la déshydrogénation de l'éthylbenzène“. Toulouse, INPT, 1987. http://www.theses.fr/1987INPT024G.
Der volle Inhalt der QuelleJubelin, Grégory. „Formation de biofilms par Escherichia coli K-12 : rôle des systèmes à deux composants dans la synthèse des curli“. Lyon, INSA, 2005. http://theses.insa-lyon.fr/publication/2005ISAL0019/these.pdf.
Der volle Inhalt der QuelleIn natural ecosystems, bacteria have a remarkable tendency to adhere to surfaces within microbial consortia called biofilms. In order to prevent colonization of surfaces, it is necessary to know bacterial mechanisms involved in biofilm formation. The aims of this work were to identify and to classify regulatory mechanisms that control synthesis of curli, a structure of attachment, according to medium osmolarity and integrity of bacterial membrane. We discovered that the two-component systems EnvZ/OmpR, CpxA/CpxR and RcsC/RcsB play a fundamental role in the transcriptional control of curli genes with complexes balances between activators and repressors. Analysis of the expression, both in time and space, of the curli genes in biofilm also shows that curli are essential in each different stage of biofilm development process
Collin, Pierre-Henry. „K-théorie pour les C*-algèbres de pavages de Penrose hyperboliques“. Electronic Thesis or Diss., Université de Lorraine, 2018. http://www.theses.fr/2018LORR0319.
Der volle Inhalt der QuelleGiven a one dimensional substitution σ, one can define the continuous hull Ωσ for the R-action given by translations and so we obtain a dynamical system Ωσ,σ. If the substitution we choose is primitive, then we can construct an hyperbolic tiling on Poincaré's half-plane equiped with its standard metric \frac{\mathrm d x +\mathrm d y}{y^2}. By analogy of the standard case, we can define two continuous hulls, denoted X_P ^ N and X_{P(c)}^G, where P(c) is a colored tiling (in such fashion that the action of G is free), and the groups are denoted respectively N= \{ \mathbb{H}_2 \to \mathbb{H}_2, z \mapsto z +t, t\in \R\} and G = \{ \mathbb{H}_2 \to \mathbb{H}_2, z \mapsto a z +b,(a,b) \in \R_+ ^* \times \R\}.\par Using Jean Renault's construction of the reduced C^*-algebra of a groupoid , the results of Ian Putnam and Jared Anderson and the Morita equivalence between C((\Xi\times \R)/\As) and C(\Xi) \rtimes \Z, we describe the C^*-algebra of the hyperbolic tiling using generators and relations. Finally we obtain for the Fibonacci, Thue-Morse and Tribonacci substitutions the full description of the generators of K_* (C(X_{P(c)}^G ) \rtimes G)
Collin, Pierre-Henry. „K-théorie pour les C*-algèbres de pavages de Penrose hyperboliques“. Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0319/document.
Der volle Inhalt der QuelleGiven a one dimensional substitution $\sigma$, one can define the continuous hull $\Omega_\sigma$ for the $\R$-action given by translations and so we obtain a dynamical system $(\Omega_\sigma,\sigma)$. If the substitution we choose is primitive, then we can construct an hyperbolic tiling on Poincaré's half-plane equiped with its standard metric $\frac{\mathrm d x +\mathrm d y}{y^2}$. By analogy of the standard case, we can define two continuous hulls, denoted $X_P ^ N $ and $X_{P(c)}^G$, where $P(c)$ is a colored tiling (in such fashion that the action of $G$ is free), and the groups are denoted respectively $N= \{ \mathbb{H}_2 \to \mathbb{H}_2, z \mapsto z +t, t\in \R\}$ and $G = \{ \mathbb{H}_2 \to \mathbb{H}_2, z \mapsto a z +b,(a,b) \in \R_+ ^* \times \R\}$.\par Using Jean Renault's construction of the reduced $C^*$-algebra of a groupoid , the results of Ian Putnam and Jared Anderson and the Morita equivalence between $C((\Xi\times \R)/\As)$ and $C(\Xi) \rtimes \Z$, we describe the $C^*$-algebra of the hyperbolic tiling using generators and relations. Finally we obtain for the Fibonacci, Thue-Morse and Tribonacci substitutions the full description of the generators of $K_* (C(X_{P(c)}^G ) \rtimes G)$
Zerbo, Boureima. „Problèmes de plus courts chemins dans les NOC et leurs extensions aux cas difficiles“. Lorient, 2012. https://hal.archives-ouvertes.fr/tel-01096420.
Der volle Inhalt der QuelleWe define and study a combinatorial optimization problem and mixed-integer linear programming, that models multi-path routing in a Network-on-Chip with guaranteed traffic. Based on time division multiplexing, the model allows to avoid collisions, deadlocks and livelocks in irregular network topologies, while minimizing latency. An extension of this multi-path problem is also presented that allows dynamic reconfigurable routing at execution time. In that case, independent sets of valid routes are pre-computed in such a way they can be interchanged during execution with no impact on the existing traffic, while reusing all the vacant and free time-slot resources. A time-expanded graph approach is retained for the solution process. First, we present a set of basic operators to compute shortest paths. They can be a greedy parallel construction heuristic, neighborhood operators, and a modified Dijkstra algorithm in a time expanded graph that allows computing a single path in an occupied Noc in pseudo-polynomial time. Then, to solve all the problems, operators are introduced and combined within three iterated local search methods that can quickly generate feasible solutions, an evolutionary algorithm based on population conferring diversity solutions in search of solutions and a memetic algorithm, taking advantage of the benefits of the previous two. Experiments are done on a set of benchmarks representative of real life applications, and instances of artificial applications randomly generated from real cases, to illustrate the performance and robustness of research methods
Gohaud, Neil. „Etude ab initio des spectres vibrationnels de systèmes de grande dimension : Application aux composés (CH3X)n, avec X=Li, Na, K“. Pau, 2006. http://www.theses.fr/2006PAUU3049.
Der volle Inhalt der QuelleVibrational spectroscopy field is still quite active nowadays: actually, its quickness of acquisition and its ability to identify functional groups make it a perfectly suitable device for characterisation of very reactive and/or short-life compounds. A spectrum analysis becomes very complex with the growth of studied systems’ size and presence of parasite molecules. Thus, recent methodological breakthroughs couple together with improvements in the computing area enable from now on an accurate theoretical assessment for systems up to 4-5 atoms, but the chemist is quickly limited in his investigations when larger molecules are considered. The aim of this thesis is to provide a computing tool designed to process a direct variational algorithm, which is the only one able to treat explicitly phenomena such as resonances, on chemical systems up to 20 atoms. In order to reach this goal, a parallel coding approach has been considered. This software, called P_Anhar, has then been used to perform a complete vibrational study on a chemical family, namely the methylalkali. From a spectroscopic point of view, there is a strong discrepancy between theoretical and experimental works dealing with these systems. Using P_Anhar has brought some parts of an answer to this discrepancy, and an interpretation of reference experimental spectra is consequently proposed, in order to revisit them
Rifi, Mohamed Aziz. „Etude et conception d’un amplificateur de puissance en technologie GaN MMIC fonctionnant en bande K adapté aux systèmes de suivi d’enveloppe“. Thesis, Limoges, 2021. http://www.theses.fr/2021LIMO0019.
Der volle Inhalt der QuelleThis thesis work is part of the process of continuous improvement of the efficiency and linearity of power amplifiers in presence of signals on modulated carriers used in modern telecommunications systems. These signals have a high PAPR and a statistical envelope distribution centered below the envelope peak value. As a result, conventional power amplifiers (Class AB fixed bias) are often oversized to meet the needs of the telecom industry. The envelope tracking technique has been used to increase the PAE along the OBO (10 dB for LTE) while maintaining a constant power gain associated to a good linearity in terms of AM/AM conversion. A power amplifier design method in MMIC technology based on the use of GaN HEMTs has been developed and is used to design an APdelivering an output power of 4W and operating in K-band [17-20GHz]. The realized APwas then coupled to a digital drain bias modulator. The APand bias modulator assembly constituting an envelope tracking system called APSE was characterized in terms of efficiency and linearity in presence of modulated signals. The APSE shows very interesting performances compared to those obtained with a fixed bias AP. Indeed, at an OBO of about 7dB, in the [17-20GHz] band, the PAE is improved by [10-7.5]. The average PAE along the OBO varies between 32 and 36% over the considered band and it is associated to an EVM varying between 5 and 1.6% with a quasi-static DPD applied to the baseband signal.The characterizations of APSE have demonstrated the interest of the use of envelope tracking power amplifiers in modern telecommunications systems
Saïdi, Mohamed. „Contribution à l'étude des systèmes quinaires : Al2O3-SiO2-P2O5-M2O-H2O (M = Li, Na, K) : équilibres solides-liquides et solides-solides sous pression“. Lyon 1, 1992. http://www.theses.fr/1992LYO10128.
Der volle Inhalt der QuelleMahboubi, Sakina. „Préservation de la confidentialité des données externalisées dans le traitement des requêtes top-k“. Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS026/document.
Der volle Inhalt der QuelleOutsourcing corporate or individual data at a cloud provider, e.g. using Database-as-a-Service, is practical and cost-effective. But it introduces a major problem: how to preserve the privacy of the outsourced data, while supporting powerful user queries. A simple solution is to encrypt the data before it is outsourced. Then, to answer a query, the user client can retrieve the encrypted data from the cloud, decrypt it, and evaluate the query over plaintext (non encrypted) data. This solution is not practical, as it does not take advantage of the computing power provided by the cloud for evaluating queries.In this thesis, we consider an important kind of queries, top-k queries,and address the problem of privacy-preserving top-k query processing over encrypted data in the cloud.A top-k query allows the user to specify a number k, and the system returns the k tuples which are most relevant to the query. The relevance degree of tuples to the query is determined by a scoring function.We first propose a complete system, called BuckTop, that is able to efficiently evaluate top-k queries over encrypted data, without having to decrypt it in the cloud. BuckTop includes a top-k query processing algorithm that works on the encrypted data, stored at one cloud node,and returns a set that is proved to contain the encrypted data corresponding to the top-k results. It also comes with an efficient filtering algorithm that is executed in the cloud on encypted data and removes most of the false positives included in the set returned.When the outsourced data is big, it is typically partitioned over multiple nodes in a distributed system. For this case, we propose two new systems, called SDB-TOPK and SD-TOPK, that can evaluate top-k queries over encrypted distributed data without having to decrypt at the nodes where they are stored. In addition, SDB-TOPK and SD-TOPK have a powerful filtering algorithm that filters the false positives as much as possible in the nodes, and returns a small set of encrypted data that will be decrypted in the user side. We analyze the security of our system, and propose efficient strategies to enforce it.We validated our solutions through implementation of BuckTop , SDB-TOPK and SD-TOPK, and compared them to baseline approaches over synthetic and real databases. The results show excellent response time compared to baseline approaches. They also show the efficiency of our filtering algorithm that eliminates almost all false positives. Furthermore, our systems yieldsignificant reduction in communication cost between the distributed system nodes when computing the query result
Feld, Niels. „Faisceaux et modules de Milnor-Witt“. Thesis, Université Grenoble Alpes, 2021. http://www.theses.fr/2021GRALM001.
Der volle Inhalt der QuelleWe generalize Rost's theory of cycle modules using the Milnor-Witt K-theory instead of the classical Milnor K-theory. We obtain a (quadratic) setting to study general cycle complexes and their (co)homology groups.Moreover, we prove that the heart of Morel-Voevodsky stable homotopy category over a perfect field (equipped with its homotopy t-structure) is equivalent to the category of Milnor-Witt cycle modules.Finally, we explore a conjecture of Morel about the Bass-Tate transfers defined on the contraction of a homotopy sheaf and prove that the conjecture is true with rational coefficients. We also study the relations between (contracted) homotopy sheaves, sheaves with generalized transfers and MW-homotopy sheaves, and prove an equivalence of categories. As applications, we describe the essential image of the canonical functor that forgets MW-transfers and use theses results to discuss the conservativity conjecture in A1-homotopy due to Bachmann and Yakerson
Trad, Riadh. „Découverte d'évènements par contenu visuel dans les médias sociaux“. Electronic Thesis or Diss., Paris, ENST, 2013. http://www.theses.fr/2013ENST0030.
Der volle Inhalt der QuelleThe ease of publishing content on social media sites brings to the Web an ever increasing amount of user generated content captured during, and associated with, real life events. Social media documents shared by users often reflect their personal experience of the event. Hence, an event can be seen as a set of personal and local views, recorded by different users. These event records are likely to exhibit similar facets of the event but also specific aspects. By linking different records of the same event occurrence we can enable rich search and browsing of social media events content. Specifically, linking all the occurrences of the same event would provide a general overview of the event. In this dissertation we present a content-based approach for leveraging the wealth of social media documents available on the Web for event identification and characterization. To match event occurrences in social media, we develop a new visual-based method for retrieving events in huge photocollections, typically in the context of User Generated Content. The main contributions of the thesis are the following : (1) a new visual-based method for retrieving events in photo collections, (2) a scalable and distributed framework for Nearest Neighbors Graph construction for high dimensional data, (3) a collaborative content-based filtering technique for selecting relevant social media documents for a given event
Jeanneau, Élise. „Failure Detectors in Dynamic Distributed Systems“. Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS207.
Der volle Inhalt der QuelleDynamic systems are distributed systems in which (1) processes can join or leave the system during the run, and (2) the communication graph evolves over time. The failure detector abstraction was introduced as a way to circumvent the impossibility of solving consensus in asynchronous systems prone to crash failures. A failure detector is a local oracle that provides processes in the system with unreliable information on process failures. But a failure detector that is sufficient to solve a given problem in a static system is not necessarily sufficient to solve the same problem in a dynamic system. Additionally, some existing failure detectors cannot be implemented in dynamic systems. Therefore, it is necessary to redefine existing failure detectors and provide new algorithms. In this thesis, we provide a new definition of a failure detector for k-set agreement, and prove that it is sufficient to solve k-set agreement in dynamic systems. We also design a dynamic system model and an algorithm that implements this new failure detector. Additionally, we adapt an existing failure detector for mutual exclusion and prove that it is still the weakest failure detector to solve mutual exclusion in dynamic systems, which means that it is weaker than any other failure detector capable of solving mutual exclusion
Trad, Riadh. „Découverte d'évènements par contenu visuel dans les médias sociaux“. Thesis, Paris, ENST, 2013. http://www.theses.fr/2013ENST0030/document.
Der volle Inhalt der QuelleThe ease of publishing content on social media sites brings to the Web an ever increasing amount of user generated content captured during, and associated with, real life events. Social media documents shared by users often reflect their personal experience of the event. Hence, an event can be seen as a set of personal and local views, recorded by different users. These event records are likely to exhibit similar facets of the event but also specific aspects. By linking different records of the same event occurrence we can enable rich search and browsing of social media events content. Specifically, linking all the occurrences of the same event would provide a general overview of the event. In this dissertation we present a content-based approach for leveraging the wealth of social media documents available on the Web for event identification and characterization. To match event occurrences in social media, we develop a new visual-based method for retrieving events in huge photocollections, typically in the context of User Generated Content. The main contributions of the thesis are the following : (1) a new visual-based method for retrieving events in photo collections, (2) a scalable and distributed framework for Nearest Neighbors Graph construction for high dimensional data, (3) a collaborative content-based filtering technique for selecting relevant social media documents for a given event
Hemon, Annie. „Cristallogenèse et étude structurale dans les systèmes fluorés ternaires AF-MF2-M'F3. (A=Na,K;M=Ca,Sr,Ba,Cd;M'=Al et éléments 3d)“. Le Mans, 1991. http://www.theses.fr/1991LEMA1001.
Der volle Inhalt der QuelleIlali, Jaffar. „Contribution à l'étude des systèmes M2+F2-M+F-LnF3 : M2+ = Pb, Ba, Sr et Ca ; M+ = K, Na et Rb ; Ln = Y, La->Lu“. Grenoble 1, 1988. http://www.theses.fr/1988GRE10128.
Der volle Inhalt der QuelleSasseville, Christian. „Géochronologie K-Ar et transfert de matière le long de systèmes de failles et de fractures dans la lithosphère continentale : Cas du système de rift Saint-Laurent en relation avec le domaine allochtone des Appalaches (Québec, Canada)“. Strasbourg 1, 2008. http://www.theses.fr/2008STR1GE10.
Der volle Inhalt der QuelleBenzoni, Séverin. „Classification des filtrations dynamiques et étude des systèmes d'entropie positive“. Electronic Thesis or Diss., Normandie, 2024. https://theses.hal.science/tel-04835404.
Der volle Inhalt der QuelleIn this thesis, we explore the possible structures of measure preserving dynamical systems of the form $\bfX :=(X, \A, \mu, T)$ and their factor $\s$-algebras $\B \subset \A$. The first two chapters investigate various ways in which a factor $\s$-algebra $\B$ can sit in a dynamical system $\bfX :=(X, \A, \mu, T)$, i.e. we study some possible structures of the \emph{extension} $\A \arr \B$. In the first chapter, we consider the concepts of \emph{super-innovations} and \emph{standardness} of extensions, which are inspired from the theory of filtrations. An important focus of our work is the introduction of the notion of \emph{confined extensions}, which first interested us because they have no super-innovation. We give several examples and study additional properties of confined extensions, including several lifting results. Then, we show our main result: the existence of non-standard extensions. Finally, this result finds an application to the study of dynamical filtrations, i.e. filtrations of the form $(\F_n)_{n \leq 0}$ such that each $\F_n$ is a factor $\s$-algebra. We show that there exist \emph{non-standard I-cosy dynamical filtrations}.The second chapter furthers the study of confined extensions by finding a new kind of such extensions, in the setup of Poisson suspensions: we take an infinite $\s$-finite measure-preserving dynamical system $(X, \mu, T)$ and a compact extension $(X \times G, \mu \otimes m_G, T_\phi)$, then we consider the corresponding Poisson extension $((X \times G)^*, (\mu \otimes m_G)^*, (T_\phi)_*) \to (X^*, \mu^*, T_*)$. We give conditions under which that extension is confined and build an example which fits those conditions.Lastly, the third chapter focuses on a family of dynamical filtrations: \emph{weak Pinsker filtrations}. The existence of those filtrations on any ergodic system comes from a recent result by Austin \cite{austin}, and they present themselves as a potential tool to describe positive entropy systems. We explore the links between the asymptotic structure of weak Pinsker filtrations and the properties of the underlying dynamical system. Naturally, we also ask whether, on a given system, the structure of weak Pinsker filtrations is unique up to isomorphism. We give a partial answer, in the case where the underlying system is Bernoulli. We conclude our work by giving two explicit examples of weak Pinsker filtrations
Fuinel, Cécile. „Étude des potentialités de la transduction diélectrique de haute permittivité pour les résonateurs NEMS et MEMS“. Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30302/document.
Der volle Inhalt der QuelleSince two decades now, microscopic electronic devices including moving parts, called MicroElectroMechanical Systems (MEMS) have had a growing impact on industry and daily lives. Their range of application is already wide: from actuators (inkjet print heads, digital cinema projectors, etc.) to mechanical sensors (microphones, accelerometers, etc.). There is a growing research effort in the biosensing field as well. One of the main challenges for this application is to integrate a miniaturized and robust element to a vibrating beam-like structure, in order to achieve electromechanical actuation and detection, i.e. to convert an electrical signal into vibration and vice versa. In this work, we studied the integration of three dielectric materials on silicon microcantilevers, and successfully demonstrated the feasibility of simultaneous flexural actuation and detection of the structures by mean of dielectric transduction. Those results are one step forward the elaboration of mature detection systems
Pruvost-Bonnaillie, Claire. „Etude de la combustion catalytique de particules carbonées sur des systèmes oxydes : CeO2, ZrO2, TiO2 et Al2O3, promus ou non par des ajouts d'ions Cu2+ et/ou K+“. Littoral, 2001. http://www.theses.fr/2001DUNK0077.
Der volle Inhalt der QuelleGouné, Mohamed. „Etude et caractérisation de la diffusion de l'azote à 843 K dans les systèmes binaires Fe-N et ternaires Fe-N-V et Fe-N-Mn : modélisation des phénomènes de diffusion-précipitation“. Vandoeuvre-les-Nancy, INPL, 2001. http://www.theses.fr/2001INPL011N.
Der volle Inhalt der QuelleHaider, Muhammad Zulqurnain. „Analysis of molecular mechanisms involved in exchange of nutrients between the fungus and the host plant within the ectomycorrhizal symbiosis“. Thesis, Montpellier, SupAgro, 2011. http://www.theses.fr/2011NSAM0042.
Der volle Inhalt der QuelleThe mycorrhizal symbiosis made it possible the first plants to conquest emerged lands and is a major biological phenomenon of terrestrial ecosystems. The fungal partner efficiently takes up nutritive ions from the soil solution and transfers them to the host plants in exchange for photosynthetates. However, despite the importance of this symbiosis on ecosystem productivity, our knowledge about molecular processes controlling this symbiotic interaction and solute transports at the membrane level is very scarce. The objective of the project aims at dissecting part of the molecular mechanisms required for a functional ectomycorrhizal symbiosis associated with most of the woody species from boreal and temperate forests, by focusing on K+ exchanges occurring through the continuum soil-hyphae-plant. The general aim of the project is to gain new insights into the molecular mechanisms responsible for the polarization and differentiation of the plasma membrane between the site of nutrient uptake and the site of efflux into the apoplastic space in the ectomycorrhizal root. The team "Canaux Ioniques – Ion channels" has obtained an EST library of the fungus Hebeloma cylindrosporum (1) and has identified and characterized a potassium transporter of the Trk family (2). Also a Shaker-type potassium cannel was identified within the EST library but it is not yet functionally characterized. A second transcript was found from this channel with a longer N-terminus compared to the first transcript isolated in the beginning. Also, a sugar transporter was identified among the ESTs that could participate in the absorption of sugars, coming from the host plant, by the fungus. The objective of the PhD thesis is the functional characterization of these fungal transport systems as well as their localization. The functional characterization of these candidate genes will be accomplished using heterologous expression systems (Xenopus oocytes, COS cells, complementation of yeast mutants) and by the means of electrophysiology. Localization of genes within the fungus being in symbiotic interaction with the host plant, the tree Pinus pinaster, will help to better understand the role of the transport systems. The differentiation of the fungus, when establishing symbiosis, into the specialized interfaces soil-fungus and fungal cell- host plant cell within the ectomycorrhiza (Hartig net) is probably accompanied by a specific expression of transport proteins and ion channels
El, chall Rida. „Récepteur itératif pour les systèmes MIMO-OFDM basé sur le décodage sphérique : convergence, performance et complexité“. Thesis, Rennes, INSA, 2015. http://www.theses.fr/2015ISAR0019/document.
Der volle Inhalt der QuelleRecently, iterative processing has been widely considered to achieve near-capacity performance and reliable high data rate transmission, for future wireless communication systems. However, such an iterative processing poses significant challenges for efficient receiver design. In this thesis, iterative receiver combining multiple-input multiple-output (MIMO) detection with channel decoding is investigated for high data rate transmission. The convergence, the performance and the computational complexity of the iterative receiver for MIMO-OFDM system are considered. First, we review the most relevant hard-output and soft-output MIMO detection algorithms based on sphere decoding, K-Best decoding, and interference cancellation. Consequently, a low-complexity K-best (LCK- Best) based decoder is proposed in order to substantially reduce the computational complexity without significant performance degradation. We then analyze the convergence behaviors of combining these detection algorithms with various forward error correction codes, namely LTE turbo decoder and LDPC decoder with the help of Extrinsic Information Transfer (EXIT) charts. Based on this analysis, a new scheduling order of the required inner and outer iterations is suggested. The performance of the proposed receiver is evaluated in various LTE channel environments, and compared with other MIMO detection schemes. Secondly, the computational complexity of the iterative receiver with different channel coding techniques is evaluated and compared for different modulation orders and coding rates. Simulation results show that our proposed approaches achieve near optimal performance but more importantly it can substantially reduce the computational complexity of the system. From a practical point of view, fixed-point representation is usually used in order to reduce the hardware costs in terms of area, power consumption and execution time. Therefore, we present efficient fixed point arithmetic of the proposed iterative receiver based on LC-KBest decoder. Additionally, the impact of the channel estimation on the system performance is studied. The proposed iterative receiver is tested in a real-time environment using the MIMO WARP platform
Chouaibi, Nour-Eddine. „Etude thermochimique des systèmes K-Ga, Rb-Ga et Cs-Ga : Contribution à l'étude structurale des phases intermétalliques gallium - métaux alcalins (Li, Na) - éléments des groupes 11 et 12 (Cu, Zn, Cd et Au)"“. Montpellier 2, 1993. http://www.theses.fr/1993MON20055.
Der volle Inhalt der QuelleMittal, Nupur. „Data, learning and privacy in recommendation systems“. Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S084/document.
Der volle Inhalt der QuelleRecommendation systems have gained tremendous popularity, both in academia and industry. They have evolved into many different varieties depending mostly on the techniques and ideas used in their implementation. This categorization also marks the boundary of their application domain. Regardless of the types of recommendation systems, they are complex and multi-disciplinary in nature, involving subjects like information retrieval, data cleansing and preprocessing, data mining etc. In our work, we identify three different challenges (among many possible) involved in the process of making recommendations and provide their solutions. We elaborate the challenges involved in obtaining user-demographic data, and processing it, to render it useful for making recommendations. The focus here is to make use of Online Social Networks to access publicly available user data, to help the recommendation systems. Using user-demographic data for the purpose of improving the personalized recommendations, has many other advantages, like dealing with the famous cold-start problem. It is also one of the founding pillars of hybrid recommendation systems. With the help of this work, we underline the importance of user’s publicly available information like tweets, posts, votes etc. to infer more private details about her. As the second challenge, we aim at improving the learning process of recommendation systems. Our goal is to provide a k-nearest neighbor method that deals with very large amount of datasets, surpassing billions of users. We propose a generic, fast and scalable k-NN graph construction algorithm that improves significantly the performance as compared to the state-of-the art approaches. Our idea is based on leveraging the bipartite nature of the underlying dataset, and use a preprocessing phase to reduce the number of similarity computations in later iterations. As a result, we gain a speed-up of 14 compared to other significant approaches from literature. Finally, we also consider the issue of privacy. Instead of directly viewing it under trivial recommendation systems, we analyze it on Online Social Networks. First, we reason how OSNs can be seen as a form of recommendation systems and how information dissemination is similar to broadcasting opinion/reviews in trivial recommendation systems. Following this parallelism, we identify privacy threat in information diffusion in OSNs and provide a privacy preserving algorithm for the same. Our algorithm Riposte quantifies the privacy in terms of differential privacy and with the help of experimental datasets, we demonstrate how Riposte maintains the desirable information diffusion properties of a network
Servajean, Maximilien. „Recommandation diversifiée et distribuée pour les données scientifiques“. Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20216/document.
Der volle Inhalt der QuelleIn many fields, novel technologies employed in information acquisition and measurement (e.g. phenotyping automated greenhouses) are at the basis of a phenomenal creation of data. In particular, we focus on two real use cases: plants observations in botany and phenotyping data in biology. Our contributions can be, however, generalized to Web data. In addition to their huge volume, data are also distributed. Indeed, each user stores their data in many heterogeneous sites (e.g. personal computers, servers, cloud); yet he wants to be able to share them. In both use cases, collaborative solutions, including distributed search and recommendation techniques, could benefit to the user.Thus, the global objective of this work is to define a set of techniques enabling sharing and discovery of data in heterogeneous distributed environment, through the use of search and recommendation approaches.For this purpose, search and recommendation allow users to be presented sets of results, or recommendations, that are both relevant to the queries submitted by the users and with respect to their profiles. Diversification techniques allow users to receive results with better novelty while avoiding redundant and repetitive content. By introducing a distance between each result presented to the user, diversity enables to return a broader set of relevant items.However, few works exploit profile diversity, which takes into account the users that share each item. In this work, we show that in some scenarios, considering profile diversity enables a consequent increase in results quality: surveys show that in more than 75% of the cases, users would prefer profile diversity to content diversity.Additionally, in order to address the problems related to data distribution among heterogeneous sites, two approaches are possible. First, P2P networks aim at establishing links between peers (nodes of the network): creating in this way an overlay network, where peers directly connected to a given peer p are known as his neighbors. This overlay is used to process queries submitted by each peer. However, in state of the art solutions, the redundancy of the peers in the various neighborhoods limits the capacity of the system to retrieve relevant items on the network, given the queries submitted by the users. In this work, we show that introducing diversity in the computation of the neighborhood, by increasing the coverage, enables a huge gain in terms of quality. By taking into account diversity, each peer in a given neighborhood has indeed, a higher probability to return different results given a keywords query compared to the other peers in the neighborhood. Whenever a query is submitted by a peer, our approach can retrieve up to three times more relevant items than state of the art solutions.The second category of approaches is called multi-site. Generally, in state of the art multi-sites solutions, the sites are homogeneous and consist in big data centers. In our context, we propose an approach enabling sharing among heterogeneous sites, such as small research teams servers, personal computers or big sites in the cloud. A prototype regrouping all contributions have been developed, with two versions addressing each of the use cases considered in this thesis
Dubois, Michel. „Fluides crustaux : approche expérimentale et analytique : 1) détermination du solvus des systèmes H2O-MCL (M=Li, K, Rb, Cs) et 2) caractérisation et dynamique des fluides des dômes thermiques, sur l'exemple du Diapir Vellave (S-E Massif Central Francais)“. Vandoeuvre-les-Nancy, INPL, 1992. http://docnum.univ-lorraine.fr/public/INPL_T_1992_DUBOIS_M.pdf.
Der volle Inhalt der QuelleJouini, Anis. „Étude thermodynamique des systèmes : MIPO3-Y(PO3)3 (MI = Li, K et Cs) : Synthèse et détermination structurale de PrP3O9.3H2O, Pr(PO3)3 et NaLnP2O7 Propriétés optiques de Pr3+ et Nd3+ dans LnP3O9.3H2O, Ln(PO3)3 et NaLnP2O7 (Ln=Pr, Nd)“. Lyon 1, 2004. http://www.theses.fr/2004LYO10028.
Der volle Inhalt der QuelleElbrahimi, Mohamed. „Contribution à l'étude physicochimique des systèmes As2O5 (ou SO3)-M(I)2O-M(IV)O2-H2O (M(I) =K, Rb, Tl, Cs et M(IV) = Ti, Zr ou Hf) : cas de M(I)TiOAsO4 et des hydroxysulfates de Zr et Hf“. Montpellier 2, 1989. http://www.theses.fr/1989MON20159.
Der volle Inhalt der QuelleAwane, Azzouz. „Structures k-symplectiques“. Mulhouse, 1992. http://www.theses.fr/1992MULH0240.
Der volle Inhalt der QuelleCissé, Gnagna. „La notion de système dans la pensée de K. Marx : systématicité et temporalité chez K. Marx“. Poitiers, 1989. http://www.theses.fr/1989POIT5013.
Der volle Inhalt der QuelleTo the abstract, dogmatic system, who seems to be eternal, who is adverse to the individual, marx conceivably prefer the open, temporal system, whose systematic perfection is never definitely establisched. Such a system seems to be an organic totality, a dynamic circular process who thoroughly makes the best of the vitality and the freedom of the individual
Sondeck, Louis-Philippe. „Privacy and utility assessment within statistical data bases“. Electronic Thesis or Diss., Evry, Institut national des télécommunications, 2017. http://www.theses.fr/2017TELE0023.
Der volle Inhalt der QuellePersonal data promise relevant improvements in almost every economy sectors thanks to all the knowledge that can be extracted from it. As a proof of it, some of the biggest companies in the world, Google, Amazon, Facebook and Apple (GAFA) rely on this resource for providing their services. However, although personal data can be very useful for improvement and development of services, they can also, intentionally or not, harm data respondent’s privacy. Indeed, many studies have shown how data that were intended to protect respondents’ personal data were finally used to leak private information. Therefore, it becomes necessary to provide methods for protecting respondent’s privacy while ensuring utility of data for services. For this purpose, Europe has established a new regulation (The General Data Protection Regulation) (EU, 2016) that aims to protect European citizens’ personal data. However, the regulation only targets one side of the main goal as it focuses on privacy of citizens while the goal is about the best trade-off between privacy and utility. Indeed, privacy and utility are usually inversely proportional and the greater the privacy, the lower the data utility. One of the main approaches for addressing the trade-off between privacy and utility is data anonymization. In the literature, anonymization refers either to anonymization mechanisms or anonymization metrics. While the mechanisms are useful for anonymizing data, metrics are necessary to validate whether or not the best trade-off has been reached. However, existing metrics have several flaws including the lack of accuracy and the complexity of implementation. Moreover existing metrics are intended to assess either privacy or utility, this adds difficulties when assessing the trade-off between privacy and utility. In this thesis, we propose a novel approach for assessing both utility and privacy called Discrimination Rate (DR). The DR is an information theoretical approach which provides practical and fine grained measurements. The DR measures the capability of attributes to refine a set of respondents with measurements scaled between 0 and 1, the best refinement leading to single respondents. For example an identifier has a DR equals to 1 as it completely refines a set of respondents. We are therefore able to provide fine grained assessments and comparison of anonymization mechanisms (whether different instantiations of the same mechanism or different anonymization mechanisms) in terms of utility and privacy. Moreover, thanks to the DR, we provide formal definitions of identifiers (Personally Identifying Information) which has been recognized as one of the main concern of privacy regulations. The DR can therefore be used both by companies and regulators for tackling the personal data protection issues
Khennoufa, Riadh. „Coloration et radio k-étiquetage de graphes“. Dijon, 2007. http://www.theses.fr/2007DIJOS067.
Der volle Inhalt der QuelleThe work of this thesis placed in the context of graph theory which presents a study of some coloring problems and other parameters associated with them. The results are applied in issues related to telecommunications networks. Mainly, our contribution focuses on solving problems and conjectures in the literature and on the expansion of knowledge in the field. In first we present a study for different values of k of the radio k-labeling problem introduced by Chartrand et al. In 2002 which consists to assign a label to each vertex of a graph so that the difference between the labels of two vertices at distance d is at least k − d + 1. The goal is to minimize the difference between the largest and smallest label used, called span. We introduce the concept of generalized Gray Code in order to obtain exact results for some graphs. We solve the conjecture of Chartrand et al. 2002 about the antipodal number of the path. The second parameter studied is the fractional total coloring for circulant graphs which consist to assign a fractions of colors to each element (vertex or edge) instead of colors (integers). The fractional chromatic number is the a minimum ratio a/b such that we can assigne a sets of colors of size b to the elements of a graph from a set of a colors such that neighboring elements receive disjoint sets of colors. By using the definition of balanced and complete fractional stable we give for cubic circulant graphs an upper bounds on the fractional total chromatic number and for 4-regular circulant graphs we find the total chromatic number for some cases and we give the exact value of the fractional total chromatic number in most cases
Sondeck, Louis-Philippe. „Privacy and utility assessment within statistical data bases“. Thesis, Evry, Institut national des télécommunications, 2017. http://www.theses.fr/2017TELE0023/document.
Der volle Inhalt der QuellePersonal data promise relevant improvements in almost every economy sectors thanks to all the knowledge that can be extracted from it. As a proof of it, some of the biggest companies in the world, Google, Amazon, Facebook and Apple (GAFA) rely on this resource for providing their services. However, although personal data can be very useful for improvement and development of services, they can also, intentionally or not, harm data respondent’s privacy. Indeed, many studies have shown how data that were intended to protect respondents’ personal data were finally used to leak private information. Therefore, it becomes necessary to provide methods for protecting respondent’s privacy while ensuring utility of data for services. For this purpose, Europe has established a new regulation (The General Data Protection Regulation) (EU, 2016) that aims to protect European citizens’ personal data. However, the regulation only targets one side of the main goal as it focuses on privacy of citizens while the goal is about the best trade-off between privacy and utility. Indeed, privacy and utility are usually inversely proportional and the greater the privacy, the lower the data utility. One of the main approaches for addressing the trade-off between privacy and utility is data anonymization. In the literature, anonymization refers either to anonymization mechanisms or anonymization metrics. While the mechanisms are useful for anonymizing data, metrics are necessary to validate whether or not the best trade-off has been reached. However, existing metrics have several flaws including the lack of accuracy and the complexity of implementation. Moreover existing metrics are intended to assess either privacy or utility, this adds difficulties when assessing the trade-off between privacy and utility. In this thesis, we propose a novel approach for assessing both utility and privacy called Discrimination Rate (DR). The DR is an information theoretical approach which provides practical and fine grained measurements. The DR measures the capability of attributes to refine a set of respondents with measurements scaled between 0 and 1, the best refinement leading to single respondents. For example an identifier has a DR equals to 1 as it completely refines a set of respondents. We are therefore able to provide fine grained assessments and comparison of anonymization mechanisms (whether different instantiations of the same mechanism or different anonymization mechanisms) in terms of utility and privacy. Moreover, thanks to the DR, we provide formal definitions of identifiers (Personally Identifying Information) which has been recognized as one of the main concern of privacy regulations. The DR can therefore be used both by companies and regulators for tackling the personal data protection issues
Mohamed, Moutuou El-Kaïoum. „Twisted groupoid KR-theory“. Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0042/document.
Der volle Inhalt der QuelleIn his 1966's paper "Ktheory and Reality", Atiyah introduced a variant of Ktheory of complex vector bundles called KRtheory, which, in some sense, is a mixture of complex Ktheory KU, real Ktheory (also called orthogonal Ktheory) KO, and Anderson's selfconjugate Ktheory KSc. The main purpose of this thesis is to generalize that theory to the noncommutative framework of twisted groupoid Ktheory. We then introduce twisted groupoid KRtheory by using the powerful machineries of Kasparov's "real" KKtheory. Specifically, we deal with the Ktheory of graded C*algebras associated with groupoid dynamical systems endowed with involutions. Such dynamical systems are classified by the Real graded Brauer group to be defined and computed in terms of Cech cohomology classes. In this new Ktheory, we give the analogues of the fundamental results in Ktheory such as the MayerVietoris exact sequences, the Bott periodicity and the Thom isomorphism theorem
Ouarnoughi, Hamza. „Placement autonomique de machines virtuelles sur un système de stockage hybride dans un cloud IaaS“. Thesis, Brest, 2017. http://www.theses.fr/2017BRES0055/document.
Der volle Inhalt der QuelleIaaS cloud providers offer virtualized resources (CPU, storage, and network) as Virtual Machines(VM). The growth and highly competitive nature of this economy has compelled them to optimize the use of their data centers, in order to offer attractive services at a lower cost. In addition to investments related to infrastructure purchase and cost of use, energy efficiency is a major point of expenditure (2% of world consumption) and is constantly increasing. Its control represents a vital opportunity. From a technical point of view, the control of energy consumption is mainly based on consolidation approaches. These approaches, which exclusively take into account the CPU use of physical machines (PM) for the VM placement, present however many drawbacks. Indeed, recent studies have shown that storage systems and disk I/O represent a significant part of the data center energy consumption (between 14% and 40%).In this thesis we propose a new autonomic model for VM placement optimization based on MAPEK (Monitor, Analyze, Plan, Execute, Knowledge) whereby in addition to CPU, VM I/O and related storage systems are considered. Our first contribution proposes a multilevel VM I/O tracer which overcomes the limitations of existing I/O monitoring tools. In the Analyze step, the collected I/O traces are introduced in a cost model which takes into account the VM I/O profile, the storage system characteristics, and the cloud environment constraints. We also analyze the complementarity between the two main storage classes, resulting in a hybrid storage model exploiting the advantages of each. Indeed, Hard Disk Drives (HDD) represent energy-intensive and inefficient devices compared to compute units. However, their low cost per gigabyte and their long lifetime may constitute positive arguments. Unlike HDD, flash-based Solid-State Disks (SSD) are more efficient and consume less power, but their high cost per gigabyte and their short lifetime (compared to HDD) represent major constraints. The Plan phase has initially resulted in an extension of CloudSim to take into account VM I/O, the hybrid nature of the storage system, as well as the implementation of the previously proposed cost model. Secondly, we proposed several heuristics based on our cost model, integrated and evaluated using CloudSim. Finally, we showed that our contribution improves existing approaches of VM placement optimization by a factor of three
Gillier, Thomas. „Comprendre la génération des objets de coopération interentreprises par une théorie des co-raisonnements de conception : vers une nouvelle ingénierie des partenariats d'exploration technologique“. Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL021N/document.
Der volle Inhalt der QuelleFor contemporary organizations, exploratory partnerships constitute opportunities to open their portfolio partnership and to embrace objects increasingly innovative and cross-functional. But, in such new forms of R&D relationships, a major crisis is caused by the fact that the common purpose is unknown at the beginning and need to be designed during the cooperation process.From a single-case study of a cross-industrial technological exploratory partnership, MINATEC IDEAs Laboratory, that research explains how heterogeneous actors reach shared objectives and launch together innovation projects.In order to understand and to model those collective objects, we propose the Matching/Building model. Based on the recent advances of the C-K Design Theory, our model describes interactions patterns between the partners’ design reasoning during their cooperation.Furthermore, that research highlights two methodological tools for enhancing cooperation in innovation : OPERA is a cartographic system to manage innovation projects and to master the evolution of the cooperation, D4 method permits to co-innovate by challenging the identity of emerging technology
Tchuente, Dieudonné. „Modélisation et dérivation de profils utilisateurs à partir de réseaux sociaux : approche à partir de communautés de réseaux k-égocentriques“. Toulouse 3, 2013. http://thesesups.ups-tlse.fr/1972/.
Der volle Inhalt der QuelleIn most systems that require user modeling to adapt information to each user's specific need, a user is usually represented by a user profile in the form of his interests. These interests are learnt and enriched over time from users interactions with the system. By the evolving nature of user's interests, the user's profile can never be considered fully known by a system. This partial knowledge of the user profile at any time t significantly reduces the performance of adaptive systems, when the user's profile contains no or only some information. This drawback is particularly most recurrent for new users in a system (time t = 0, also called cold start problem) and for less active users. To address this problem, several studies have explored data sources other than those produced by the user in the system: activities of users with similar behavior (e. G. Collaborative filtering techniques) or data generated by the user in other systems (e. G. , multi-application user's profiles, multiple identities management systems). By the recent advent of Social Web and the explosion of online social networks sites, social networks are more and more studied as an external data source that can be used to enrich users' profiles. This has led to the emergence of new social information filtering techniques (e. G. Social information retrieval, social recommender systems). Current studies on social information filtering show that this new research field is very promising. However, much remains to be done to complement and enhance these studies. We particularly address two drawbacks: (i) each existing social information filtering approach is specific in its field scope (and associated mechanisms), (ii) these approaches unilaterally use profiles of individuals around the user in the social network to improve traditional information filtering systems. To overcome these drawbacks in this thesis, we aim at defining a generic social model of users' profiles that can be reusable in many application domains and for several social information filtering mechanisms, and proposing optimal techniques for enriching user's profile from the user's social network. We rely on existing studies in social sciences to propose a communities (rather than individuals) based approach for using individuals around the user in a specific part of his social network, to derive his social profile (profile that contains user's interest derived from his social network). The significant part of the user's social network used in our studies is composed of individuals located at a maximum distance k (in the entire social network) from the user, and relationships between these individuals (k-egocentric network). Two evaluations of the proposed approach based on communities in k-egocentric networks have been conducted in the online social network Facebook and the co-authors network DBLP. They allow us to demonstrate the relevance of the proposal with respect to existing individual based approaches, and the impact of structural measures such as the centrality of communities (degree or proximity) or user's k-egocentric network density, on the quality of results. Our approach opens up many opportunities for future studies in social information filtering and many application domains as well as on the Web (e. G. Personalization of search engines, recommender systems in e-commerce, adaptive systems in e-Learning environment) or in Intranets business systems (e. G. Behavioral analysis in networks of subscribers telecom customers, detection of abnormal behavior network bank customers, etc. )
Salah, Abdellatif. „Schémas de décodage MIMO à complexité réduite“. Phd thesis, Paris, Télécom ParisTech, 2010. https://pastel.hal.science/pastel-00682392.
Der volle Inhalt der QuelleThe use of MIMO antennas is a technique that allows to exploit in a very effective way the spatial and temporal diversity in certain systems of communication, of which the wireless communication systems. The main advantage of this technique is a good spectral efficiency. Nowadays, the mobile radio channel is increasingly used to transmit all type of information and methods allowing a more effective use of the spectrum have a fundamental importance. Today, the well-known reception algorithms are very complex, even as regards the MIMO systems with the simplest space-time codes. This complexity remains one of the main obstacles in the real exploitation of this technique. This thesis presents a detailed study of the complexity, the performance and the most interesting aspects of the behavior of the reception algorithms for MIMO decoding. This study presents a quick mean for a possible architectural conception adapted to this problem. Among the subjects presented in this thesis, an in-depth study of the performance and the complexity of these algorithms was realized, having for objective to acquire enough knowledge to be able to choose, among the large number of known algorithms, the best adapted to every particular system. Improvements in the known algorithms were also proposed and analyzed
Salah, Abdellatif. „Schémas de décodage MIMO à Complexité Réduite“. Phd thesis, Télécom ParisTech, 2010. http://pastel.archives-ouvertes.fr/pastel-00682392.
Der volle Inhalt der QuelleMathiaud, Julien. „Étude de systèmes de type gaz-particules“. Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2006. http://tel.archives-ouvertes.fr/tel-00133645.
Der volle Inhalt der QuelleAkar, S. „Études des désintégrations B -> K pi pi gamma avec l'expérience Babar : hélicité du photon et structure résonante du système K pi pi“. Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00998252.
Der volle Inhalt der QuelleMohamed, Moutuou El-Kaïoum. „Twisted groupoid KR-theory“. Electronic Thesis or Diss., Université de Lorraine, 2012. http://www.theses.fr/2012LORR0042.
Der volle Inhalt der QuelleIn his 1966's paper "Ktheory and Reality", Atiyah introduced a variant of Ktheory of complex vector bundles called KRtheory, which, in some sense, is a mixture of complex Ktheory KU, real Ktheory (also called orthogonal Ktheory) KO, and Anderson's selfconjugate Ktheory KSc. The main purpose of this thesis is to generalize that theory to the noncommutative framework of twisted groupoid Ktheory. We then introduce twisted groupoid KRtheory by using the powerful machineries of Kasparov's "real" KKtheory. Specifically, we deal with the Ktheory of graded C*algebras associated with groupoid dynamical systems endowed with involutions. Such dynamical systems are classified by the Real graded Brauer group to be defined and computed in terms of Cech cohomology classes. In this new Ktheory, we give the analogues of the fundamental results in Ktheory such as the MayerVietoris exact sequences, the Bott periodicity and the Thom isomorphism theorem
Gaujour, Etienne. „Evaluation des sources d'espèces et des déterminants de la diversité végétale des parcelles agricoles : interchamps, stock semencier, pratiques agricoles et paysage de l'Installation Expérimentale Inra ASTER Mirecourt“. Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL020N/document.
Der volle Inhalt der QuelleOne of the means to offset the decrease of pesticide use is to favour agro-ecological services of plant diversity. In this aim, farmer will have to adapt its farming management. My work partly answers to the following applied objective: to bring to the farmer some advices for the management of plant diversity on the farm territory. I have two scientific objectives: i) to verify if field boundaries and soil seed bank are potential sources of plant species for field centres; ii) to quantify the relative influence of dynamics of two factor groups, characterized as field paths, on plant diversity: farming practices and characteristics of landscape mosaïc.I have carried out this study on the experimental farm of INRA ASTER Mirecourt. Its farming systems (mixed crop-dairy systems) have been converted to organic farming since 2004. I have characterized vegetation - established vegetation in field boundaries and in field centres, and vegetation in the soil seed bank - of permanent grasslands and arable fields with complementary approaches: taxonomical approach based on the species, and functional approach based on seven functional properties about dispersal, establishment and persistence of plant species. I have characterized field paths, along nine years, either from farming practices set up on field, either from annual characteristics of landscape mosaïc. I have represented this landscape mosaïc as a mosaïc of distinct land-uses. All of them and their spatialization have been determined from farmer surveys or landscape observations.My results show that soil seed bank and field bboundaries are not potential sources of plant species for field centres, in both permanent grasslands and arable fields. On the other hand, they are efficient refuges for a large part of grassland species. According to my results, I hypothesize that field boudaries are species sinks in arable fields. I also highlight that functional gradient of grassland vegetation in the field edge, between field margins and field centres, is spread until 2 m only.Finally, plant diversity in studied fields is mainly influenced by field path according landscape mosaïc and by farming practices set up the same year of vegetation sampling. Soil characteristics have a minor influence. These three groups of influent factors explain more than 75 % of the functional composition variability of the vegetation in field centres.The management of plant diversity in agricultural fields of a given farm can be partly reach by the farmer. However, according to the effects of field paths about landscape mosaïc, it is necessary to set up a collective management of plant diversity with all actors sharing the studied territory
Bellachehab, Anass. „Pairwise gossip in CAT(k) metric spaces“. Thesis, Evry, Institut national des télécommunications, 2017. http://www.theses.fr/2017TELE0017/document.
Der volle Inhalt der QuelleThis thesis deals with the problem of consensus on networks. Networks under study consists of identical agents that can communicate with each other, have memory and computational capacity. The network has no central node. Each agent stores a value that, initially, is not known by other agents. The goal is to achieve consensus, i.e. all agents having the same value, in a fully distributed way. Hence, only neighboring agents can have direct communication. This problem has a long and fruitful history. If all values belong to some vector space, several protocols are known to solve this problem. A well-known solution is the pairwise gossip protocol that achieves consensus asymptotically. It is an iterative protocol that consists in choosing two adjacent nodes at each iteration and average them. The specificity of this Ph.D. thesis lies in the fact that the data stored by the agents does not necessarily belong to a vector space, but some metric space. For instance, each agent stores a direction (the metric space is the projective space) or position on a sphere (the metric space is a sphere) or even a position on a metric graph (the metric space is the underlying graph). Then the mentioned pairwise gossip protocols makes no sense since averaging implies additions and multiplications that are not available in metric spaces: what is the average of two directions, for instance? However, in metric spaces midpoints sometimes make sense and when they do, they can advantageously replace averages. In this work, we realized that, if one wants midpoints to converge, curvature matters. We focused on the case where the data space belongs to some special class of metric spaces called CAT(k) spaces. And we were able to show that, provided initial data is "close enough" is some precise meaning, midpoints-based gossip algorithm – that we refer to as Random Pairwise Midpoints - does converge to consensus asymptotically. Our generalization allows to treat new cases of data spaces such as positive definite matrices, the rotations group and metamorphic systems
Harrus, Ilana. „Violation de CP dans le système K⁰-K⁰ : étude et réduction du bruit de fond chargé à l'aide d'un détecteur à rayonnement de transition“. Paris 11, 1989. http://www.theses.fr/1989PA112123.
Der volle Inhalt der QuelleThis work has been performed for the NA31 experiment at CERN whose goal is a high precision measurement of the parameter Ɛ '/ Ɛ reflecting direct CP-violation in the K0- K0 system. This work is concerned with the calibration and the study of the performance of the transition radiation detector, TRD, added recently to the experiment. The TRD provides an important increase in the pion/electrons separation. This allows a significant reduction in the systematic uncertainty in the background substaction of the K0L to two charged pions decay mode which is dominated by semi leptonics decays. A complete calibration of this detector has been performed. Energy pulseheight response for various detectors parameters is reviewed. After ail corrections, electron rejection efficiency is shown. We analyze then, the semi-leptonic charged background
Bellachehab, Anass. „Pairwise gossip in CAT(k) metric spaces“. Electronic Thesis or Diss., Evry, Institut national des télécommunications, 2017. http://www.theses.fr/2017TELE0017.
Der volle Inhalt der QuelleThis thesis deals with the problem of consensus on networks. Networks under study consists of identical agents that can communicate with each other, have memory and computational capacity. The network has no central node. Each agent stores a value that, initially, is not known by other agents. The goal is to achieve consensus, i.e. all agents having the same value, in a fully distributed way. Hence, only neighboring agents can have direct communication. This problem has a long and fruitful history. If all values belong to some vector space, several protocols are known to solve this problem. A well-known solution is the pairwise gossip protocol that achieves consensus asymptotically. It is an iterative protocol that consists in choosing two adjacent nodes at each iteration and average them. The specificity of this Ph.D. thesis lies in the fact that the data stored by the agents does not necessarily belong to a vector space, but some metric space. For instance, each agent stores a direction (the metric space is the projective space) or position on a sphere (the metric space is a sphere) or even a position on a metric graph (the metric space is the underlying graph). Then the mentioned pairwise gossip protocols makes no sense since averaging implies additions and multiplications that are not available in metric spaces: what is the average of two directions, for instance? However, in metric spaces midpoints sometimes make sense and when they do, they can advantageously replace averages. In this work, we realized that, if one wants midpoints to converge, curvature matters. We focused on the case where the data space belongs to some special class of metric spaces called CAT(k) spaces. And we were able to show that, provided initial data is "close enough" is some precise meaning, midpoints-based gossip algorithm – that we refer to as Random Pairwise Midpoints - does converge to consensus asymptotically. Our generalization allows to treat new cases of data spaces such as positive definite matrices, the rotations group and metamorphic systems
Champion, Adrien. „Collaboration de techniques formelles pour la vérification de propriétés de sûreté sur des systèmes de transition“. Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0001/document.
Der volle Inhalt der QuelleThis work studies the verification of software components in avionics critical embedded systems. As the failure of suchsystems can have catastrophic consequences, it is mandatory to make sure they are consistent with their specification.Formal verification consists in proving that a system respects its specification if it does, or to produce a counterexample if itdoes not. Current methods are unable to handle the verification problems stemming from realistic systems. Discoveringadditional information (invariants) on the system can however restrict the search space enough to strengthen the proofobjective: the information discovered allow to "easily" reach a conclusion. We define a parallel architecture for invariantdiscovery methods allowing them to collaborate around a k-induction engine. In this context we propose a new heuristic forthe generation of potential invariants by combining an iterated preimage calculus by quantifier elimination with convexhull computations, called HullQe. We show that HullQe is able to automatically strengthen proof objectives correspondingto safety properties on widespread design patterns in our field. To the best of our knowledge, these systems elude currenttechniques. We also detail our improvements to the quantifier elimination algorithm by David Monniaux in 2008, so that itscales to computing preimages on our systems. Our formal framework Stuff is an implementation of the parallel architecturewe propose in which we implemented not only HullQe, but also a template-based invariant discovery technique, and ageneralisation to Property Directed Reachability to linear real arithmetic and integer octagons