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Fleury, Guillaume. "Des polyrotaxanes de haute masse moléculaire au réseau topologique : Les gels à points de réticulation glissants". Université Louis Pasteur (Strasbourg) (1971-2008), 2005. https://publication-theses.unistra.fr/public/theses_doctorat/2005/FLEURY_Guillaume_2005.pdf.
Pełny tekst źródłaA new class of supramolecular networks, where the crosslink points are not fixed but sliding, has been recently proposed and developed by Okumura and Ito. Their structure is based on intermoleculary crosslinked α-cyclodextrins / poly(ethylene-glycol) precursor polyrotaxanes. The intermolecular crosslinking between the polyrotaxane precursors leads to the formation of a supramolecular sliding network, the sliding gel. These specific networks are synthesized in two main steps: i) the formation of polyrotaxane precursors where the macrocycles are threaded along a template polymer chain; ii) the intermolecular crosslinking of some macrocycles. The sliding gels are expected to have very unusual physical / mechanical properties due to the theoretical ability of the crosslink points to slide along the polymer chain. The aim of this PhD work is to have more insight into the original properties of the sliding gels. For this purpose a controlled synthesis of the topological networks have been carried out and leads to a control of the complexation degree of the polyrotaxanes and of the crosslinking density of the topological network. The characterization of the sliding gels was carried out In order to explain the structure / properties relationships and to highlight on the sliding motion of the crosslink points. In particular the viscoelastic behaviour of the sliding gels in DMSO at low frequencies has revealed all the potential of the sliding crosslink points and underlines the high ability to relax with very low viscous dissipation of this material
Vyt, Dany. "Mesure de la performance d'un réseau de points de vente : une approche géomarketing par la méthode DEA". Rennes 1, 2006. http://www.theses.fr/2006REN1G006.
Pełny tekst źródłaBouju, Alain. "Etiquetage et poursuite de points caractéristiques d'un objet 3D par des méthodes connexionistes". Toulouse, ENSAE, 1993. http://www.theses.fr/1993ESAE0017.
Pełny tekst źródłaBurdin, Sébastien. "Le réseau Kondo à basse température : du liquide de Fermi au liquide de spin". Université Joseph Fourier (Grenoble), 2001. http://www.theses.fr/2001GRE10101.
Pełny tekst źródłaThis thesis revolves around a main subject : the theoretical study of the Kondo effect in heavy fermions when the magnetic impurity concentration is high. In the first part, the influence of the variation of the concentration of conducting electrons on the Kondo lattice is studied at low temperature (exhaustion problem). This effect can be observed experimentaly in some Cerium and Uranium compounds, whose coherence temperature can be considerably small compared to the predictions of single impurity models. The study is made both analyticaly and numericaly in the "large-N" limit, where N is the number of spin components. Whereas the single impurity models are caracterised at low temperature by a single energy scale, Tk, this thesis confirms the existence for the Kondo lattice of a second scale T*, caracterising the appearance of the Fermi liquid behavior. In the second part, the effects of disorder and magnetic frustration are studied analyticaly, within the dynamical mean field theory formalism, in the "large-N" limit. A quantum critical point (QCP) is obtained between a heavy Fermi liquid regime and a spin liquid regime. The physical properties of the system are computed in the Kondo phase. In particular, a strong decrease of T* and Tk is obtained in the vicinity of the QCP. This result is correlated with the large effective mass that has been experimentaly mesured for the compound LiV24. Finaly, the third part presents a preliminary study and the outline of the computation procedure leading to the numerical determination of the magnetic phase diagram of the periodic Anderson Model, using the dynamical mean field theory method
Hora, Diego Neves da. "Predicting home Wi-Fi QoE from passive measurements on commodity access points". Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066599/document.
Pełny tekst źródłaPoor Wi-Fi quality can disrupt home users' internet experience, or the Quality of Experience (QoE). Detecting when Wi-Fi degrades QoE is valuable for residential Internet Service Providers (ISPs) as home users often hold the ISP responsible whenever QoE degrades. Yet, ISPs have little visibility within the home to assist users. This thesis designs and evaluates techniques to passively monitor Wi-Fi quality on commodity access points (APs) and predict when Wi-Fi quality degrades internet application QoE. Our first contribution is the design and evaluation of a method that estimates Wi-Fi link capacity. We extend previous models, suited for 802.11a/b/g networks, to work on 802.11n networks using passive measurements. Our second contribution is the design and evaluation of predictors of the effect of Wi-Fi quality on QoE of four popular applications: web browsing, YouTube, audio and video real time communication. Our third contribution is the design of a method to identify poor QoE events. We use K-means clustering to identify instances where the QoE predictors estimate that all studied applications perform poorly. Then, we classify poor QoE events as short, intermittent, and consistent poor QoE events. Finally, our fourth contribution is to apply our predictors to Wi-Fi metrics collected over one week from 832 APs of customers of a large residential ISP. Our results show that QoE is good on the vast majority of samples of the deployment, still we find 9% of poor QoE samples. Worse, approximately 10% of stations have more than 25% poor QoE samples. In some cases, we estimate that Wi-Fi quality causes poor QoE for many hours, though in most cases poor QoE events are short
Paradis, François. "Points de vue alternatifs en simulations numériques de la physique quantique". Thesis, Université Laval, 2007. http://www.theses.ulaval.ca/2007/24586/24586.pdf.
Pełny tekst źródłaHora, Diego Neves da. "Predicting home Wi-Fi QoE from passive measurements on commodity access points". Electronic Thesis or Diss., Paris 6, 2017. http://www.theses.fr/2017PA066599.
Pełny tekst źródłaPoor Wi-Fi quality can disrupt home users' internet experience, or the Quality of Experience (QoE). Detecting when Wi-Fi degrades QoE is valuable for residential Internet Service Providers (ISPs) as home users often hold the ISP responsible whenever QoE degrades. Yet, ISPs have little visibility within the home to assist users. This thesis designs and evaluates techniques to passively monitor Wi-Fi quality on commodity access points (APs) and predict when Wi-Fi quality degrades internet application QoE. Our first contribution is the design and evaluation of a method that estimates Wi-Fi link capacity. We extend previous models, suited for 802.11a/b/g networks, to work on 802.11n networks using passive measurements. Our second contribution is the design and evaluation of predictors of the effect of Wi-Fi quality on QoE of four popular applications: web browsing, YouTube, audio and video real time communication. Our third contribution is the design of a method to identify poor QoE events. We use K-means clustering to identify instances where the QoE predictors estimate that all studied applications perform poorly. Then, we classify poor QoE events as short, intermittent, and consistent poor QoE events. Finally, our fourth contribution is to apply our predictors to Wi-Fi metrics collected over one week from 832 APs of customers of a large residential ISP. Our results show that QoE is good on the vast majority of samples of the deployment, still we find 9% of poor QoE samples. Worse, approximately 10% of stations have more than 25% poor QoE samples. In some cases, we estimate that Wi-Fi quality causes poor QoE for many hours, though in most cases poor QoE events are short
Askri, Aymen. "The uplink reception and downlink transmission in MU-MIMO for 5G". Electronic Thesis or Diss., Institut polytechnique de Paris, 2021. http://www.theses.fr/2021IPPAT006.
Pełny tekst źródłaMultiple-input multiple-output (MIMO) technologies were developed to increase system capacity and offer better link reliability. They allow a dense network architecture that will allow many users to connect in the same area without experiencing slowdowns. 5G networks and beyond will use these MIMO technologies with many small antennas allowing the beam to be focused on a given area. Coupled with high-frequency bands, the use of these antennas will significantly increase throughput.In such systems, multi-user (MU)-MIMO detection in the uplink reception and MU-MIMO precoding in the downlink transmission enable separating user data streams and pre-cancelling interference. However, some challenges have to be met under realistic conditions such as the reasonable complexity of the decoding and precoding processes, the erroneous channel knowledge, and the adjacent cell interference. This thesis addresses all these limitations above for the uplink reception and the downlink transmission in MU-MIMO systems.In the uplink reception, we study the well-known sphere decoding (SD) algorithm for MIMO detection. We seek to reduce its complexity which increases exponentially with the number of antennas and the constellation size. Thus, we profit from recent advances in neural networks (NNs) to develop the low-complexity NN assisted SD. We also propose the block recursive MIMO decoding, which achieves almost the maximum likelihood (ML) performance. Using deep neural networks (DNNs), we suggest a new and low complex scheme for signal processing and cloud-RAN (C-RAN) detection. This DNN scheme aims to mimic the whole transmission in uplink C-RAN, which considers the quantization constraints at the radio remote units (RRUs) and the corrupted observations at the central processor (CP).In the downlink transmission, we study the non-linear vector perturbation (VP) precoding. We design the combined VP to serve multiple users with different modulation coding schemes (MCSs). We also introduce the block VP algorithm, which merges both linear and non-linear precoding to offer a tunable tradeoff between complexity and performance. To deal with the erroneous channel state information (CSI) in the downlink precoding, we develop the new CSI accuracy indicator reporting to design a novel precoder that is less sensitive to CSI errors
Smirani, Sinda. "Étude du codage réseau au niveau de la couche physique pour les canaux bidirectionnels à relais". Phd thesis, Université Paris Sud - Paris XI, 2014. http://tel.archives-ouvertes.fr/tel-00962333.
Pełny tekst źródłaLinnik, Ekaterina. "Propriétés spectrales des paraélectriques quantiques". Electronic Thesis or Diss., Amiens, 2022. http://www.theses.fr/2022AMIE0037.
Pełny tekst źródłaA quantum paraelectric SrTiO3 is a material situated in close proximity to a quantum critical point of ferroelectric transition in which the critical temperature of ferroelectric state is suppressed down to 0 K. However, the understanding of the behaviour of the phase transition in the vicinity of this point remains challenging. Here we study the solid solutions based on the SrTiO3 to approach the pre-critical regions of the phase diagram and study the outcome of the coexistence of quantum fluctuations and thermal motion. It will allow the discovery of the novel phase statements and physical properties, occurring due to competition of quantum and classical regimes. We study the crystal structure and lattice dynamics of quantum paraelectric BaxSr1 xTiO3 solid solutions using X-Ray diffraction, Raman and terahertz-infrared (THz-IR)-spectroscopies in a temperature range 4-300K. The X-Ray diffraction and Raman spectroscopy reveal the cubic-to-tetragonal non-polar structural phase transition at about 100K. At the same time, Raman spectra manifest the presence of polar modes, TO2 and TO4, normally prohibited in paraelectric phase. Emergence of these modes indicates the appearance of the polar nanoregions in a broad temperature range. The modes become more intensive at low temperatures, the temperature dependence of their intensities on cooling reveals the kink-like change of the slope from flat to steep, indicating on activation of polar nanoregions. The transmission THz-IR-spectra show, that squared frequencies of the polar TO1 soft modes, responsible for the ferroelectric transition, follow the Cochran’s behavior at high temperatures. However, at low temperatures, it does not vanish at extrapolated Curie temperature but saturates, demonstrating the plateau feature below 20K. This behavior, coherent with the known saturation of the dielectric constant, indicates that transition to ferroelectric phase in BaxSr1-xTiO3 is suppressed by quantum fluctuations and system stays in the quantum paraelectric state at very low temperatures. Using the concentration of Pb in PbxSr1-xTiO3 solid solutions as a tuning parameter and applying the combination of Raman and dielectric spectroscopy methods we approach the quantum critical point in PbxSr1-xTiO3 and study the interplay of classical and quantum phenomena in the region of criticality. We obtain the critical temperature of PbxSr1-xTiO3 and the evolution of the temperature-dependent dynamical properties of the system as a function of x to reveal the mechanism of the transition. We show that the ferroelectric transition occurs gradually through the emergence of the polar nanoregions. We study also the cubic-to-tetragonal structural transition, occurring at higher temperatures, and show that its properties are almost concentration-independent and not affected by the quantum criticality. We also study the dielectric properties for the PbxSr1-xTiO3 in detail and show that in the composition with x = 0.005, a smooth plateau is observed in the temperature dependence of the dielectric permittivity. The height of the plateau depends on the Pb concentration and gradually decreases when x increases. This plateau arises due to random quantum fluctuations of the ions which dominate at low temperatures and concentrations. At higher x, the thermal fluctuations become more pronounced; therefore the plateau disappears
Paillard, Mathieu. "Dynamique de relaxation de spin dans les boîtes quantiques auto-organisées InAs/GaAs". Toulouse, INSA, 2001. http://www.theses.fr/2001ISAT0011.
Pełny tekst źródłaWe have investigated the carrier dynamics in self-organized InAs/GaAs quantum dots structures by time-resolved photoluminescence. By performing a strict resonant excitation of the quantum dot ground state, we have directly measured the exciton radiative recombination time. At low temperature, we observe strictly no decay of both the linear and the circular luminescence polarization. This demonstrates that neither the electron, nor the hole spin relax on the exciton lifetime scale (2̃,5 ns). These experiments allow also to probe the exciton fine structure without resolving it spectrally. After optical orientation of carrier photogenerated under non resonant excitation, an unexpected increase of the quantum dot excited state luminescence polarization is observed. This effect is interpreted in terms of Pauli blocking which prevent the relaxation of an electron in the quantum dot ground state already occupied by another electron with the same spin orientation. We have developed a simple theoretical model, based on the Master Equation of Microstates, which qualitatively describes the experimental results
Wells, Jennifer. "Complexité et changement climatique : une étude épistémologique des théories de la complexité transdisciplinaires et leur apport aux phénomènes socio-écologiques". Thesis, Paris 4, 2009. http://www.theses.fr/2009PA040136/document.
Pełny tekst źródłaThis dissertation presents an epistemological analysis of complexity theories, an evaluation of their contribution, both generally and to specific domains, and a demonstration of their important contribution to climate change. The objective is to provide a description of complexity theories across the whole range of disciplines, as complexity theories continue to expand and the list of their proposed benefits continue to grow. The case study of climate change is rich, as it touches on a number of complex systems of primary significance to humanity, such as agriculture, energy, water, and the economy. The present work proposes first a definition of generalized complexity, comprised of a general framework of the field based upon six major categories. It proceeds to analyze, in light of this framework, the scientific, ethical and political dimensions of climate change. Our point of departure consists in a thorough examination of three important bodies of literature: the IPCC report “Climate Change 2007,” the “Millennium Ecosystem Assessment,” and the ethics of climate change. The dissertation shows that the use of complexity theories is necessary in order to measure in a rigorous manner the contribution, not only of the multiple aspects of different complex systems involved, but also of the framework as an ensemble, with its polyvalent signification. By examining the role and the utility of complexity theories in multiple fields at multiple scales, we reveal a series of key principles regarding the nature and usage of these theories
Struss, Quentin. "Chambres à vapeur ultra-minces en silicium embarquées pour l’atténuation de points chauds sur les dispositifs de la microélectronique". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI131.
Pełny tekst źródłaThermal management, and more precisely hotspots attenuation, have nowadays become one of the most critical aspect in the design of microelectronic components, especially in the case of compact mobile applications. The work presented in this manuscript deals with the design, the fabrication and the characterization of an ultra-thin silicon vapor chamber integrating a micropillars capillary wick. It is designed to be directly embedded on the backside of a CMOS component in order to reduce hotspots intensity. A vapor chamber is a passive phase-change cooling device, which evaporation and condensation cycles leads to significantly higher heat transfer performances compared to classical heat spreading solution. The miniaturization of such devices has been studied using analytical and numerical models and lets consider total thicknesses lower than 600 µm in the case of 1x1 cm2 chips dissipating until 10 W. A microfabrication process flow, compatible with the presence of a CMOS component on the front side, has been developed and allows the fabrication of devices from two microstructured silicon wafer, assembled by a low temperature direct bonding process. The device operating is experimentally verified and an estimation of the optimal performances, realized using a numerical model, exhibits significantly higher performances compared to a copper heat spreader with the same dimensions. An innovative collective wafer level filling and sealing approach has also been developed using Au-Au direct bonding at room temperature and allows, for the first time, the fabrication of a silicon vapor chamber with no filling hole
Khallouf, Zainab. "Secure multicast routing infrastructure : the network operator point of view". Grenoble INPG, 2006. https://tel.archives-ouvertes.fr/tel-00406511.
Pełny tekst źródłaLn this thesis we adopt the security from the multicast Network Operator's viewpoint. The kind of security required by a network operator, who manages and operates the multicast routing infrastructure, largely differs from that of end-to-end security. More specifically, the operator is concerned by service continuity no matter what happens. While many theoretically ideal proposais have been done to secure the routing protocols, they have rarely been accepted by the operator community. For instance, because they require to modify existing and widely deployed protocols, or they introduce heavy authentication mechanisms, which is in practice almost impossible to deploy in legacy networks, and even infeasible, since a corrupted host may be the source of a DoS attack, even if it has been authenticated. Ln this thesis analyze in depth the threats to the multicast infrastructure. We show that the vulnerability of the multicast model comes largely from the edge. More specifically, several attacks arise from the use of group management protocols, IGMP for IPv4 and MLD for IPv6. Ln the light of this analysis, we introduce and evaluate a simple, yet efficient filtering approach to thwart some DoS attacks that are based on IGMP or MLD flooding, and that threaten the whole operator's infrastructure
Berthomé, Pascal. "Contribution à l'algorithmique des architectures parallèles : des réseaux point-à-point aux réseaux optiques". Lyon 1, 1995. http://www.theses.fr/1995LYO10031.
Pełny tekst źródłaLamei, Kamran. "Fonction de Hilbert non standard et nombres de Betti gradués des puissances d'idéaux". Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066368/document.
Pełny tekst źródłaUsing the concept of vector partition functions, we investigate the asymptotic behavior of graded Betti numbers of powers of homogeneous ideals in a polynomial ring over a field. For a positive Z-grading, our main result states that the Betti numbers of powers is encoded by finitely many polynomials. More precisely, Z^2 can be splitted into a finite number of regions such that, in each of them, dim_k Tor^{S}_{i} (I^t,k)μ is a quasi-polynomial in (μ,t). This refines, in a graded situation, the result of Kodiyalam on Betti numbers of powers in [33]. The main statement treats the case of a power products of homogeneous ideals in a Z^d -graded algebra, for a positive grading, in the sense of [37] and it is also generalizes to I -good filtrations . In the second part , using the parametric version of Barvinok’s algorithm, we give a closed formula for non-standard Hilbert functions of polynomial rings, in low dimensions
Savard, Anne. "Codage pour les communications coopératives : Codage de source distribué et canaux à relais". Thesis, Cergy-Pontoise, 2015. http://www.theses.fr/2015CERG0774/document.
Pełny tekst źródłaThe current wireless data traffic growth cannot be handled by classical multi-hop network protocols as in interference-free wired networks, thus it has been recognized that network nodes need to cooperate in order to take advantage of source and/or channel signal correlations, which is needed to achieve fundamental capacity limits.This thesis first considers a cooperative source coding problem, namely binary source coding with coded side information (CoSI): the helper node has access to a signal that is correlated with the source and may send a compressed version on a separate link to the destination, thus rate can be saved on the main source-destination link. Using a characterization of the Hamming-space Voronoi regions of the quantizer at the helper node, an improved practical scheme based on LDPC codes is proposed.The second part of the thesis considers cooperative channel coding, where helper nodes are relays. The simplest example of such a communication is the relay channel, in which a relay node helps the source to send its message to the destination. Whereas in the source coding problem, the correlation between source and side information is given, in channel coding, the main question is to find the best relaying operation. First, a somewhat dual problem to source coding with CoSI is studied, by considering correlated noises at the relay and destination. Then, various extensions of the relay channel are characterized using upper bounds on capacity and achievable rates: the two-way relay channel with correlated noises at the relay and destinations, where two sources wish to exchange their data with the help of a relay, and the multiway relay channel with direct links, where users, grouped into fully connected clusters (users in a cluster can overhear each others' messages), wish to exchange their messages locally within a cluster with the help of one relay
Draief, Moez. "Grands Réseaux Aléatoires: comportement asymptotique et points fixes". Phd thesis, Université Paris-Diderot - Paris VII, 2005. http://tel.archives-ouvertes.fr/tel-00009919.
Pełny tekst źródłaDraief, Moez. "Grand réseaux aléatoires : Comportement asymptotique et points fixes". Paris 7, 2005. http://www.theses.fr/2005PA077201.
Pełny tekst źródłaA cornerstone result in queueing theory due to Burke states that the departure process from a stationary M/M/1 queue is a Poisson process having the same intensity as the arrival process. I proved different extensions of this theorem to the single server queue and to the storage model. Furthermore, I looked at these models in tandem in the {\em transient régime}. I showed that these models are dual in a strong fashion. Indeed I proved that the equations governing the dynamics of both models (queue and store) are the same even though the interesting variables are different whether we are interested in the queueing model or in the storage model. I use this duality to give an elegant proof, using analogies with the Robinson-Schensted-Knuth algorithm, of the property of symmetry of both Systems. Moreover I explored the correlations between the laws of the services of successive customers belonging to the same busy period. Burke's theorem can be seen as a fixed point result the Poisson process is a fixed point for the queue with exponential service times. I explored fixed points for the single server queue and the storage model in the context of large deviations where the arrivals and the services are described by means of their rate functions
Sander, Agnès. "LES POINTS - DE - RÉSEAUX COMME FORMES URBAINES.Morphogenèse et enjeux de conception". Phd thesis, Université Paris XII Val de Marne, 1995. http://tel.archives-ouvertes.fr/tel-00345093.
Pełny tekst źródłaMalgré la multiplicité des logiques à l'oeuvre dans la conception des "points-de-réseaux" (logiques d'acteurs diverses à une date donnée, mais aussi logiques successives d'un même acteur dans la durée) et malgré la diversité des sites d'implantation (dont les caractéristiques influent sur la dite conception), des procédés de régulation de la forme et de la fonction de ces points existent.
Ce résultat repose sur deux études empiriques venant compléter un cadre théorique proposé en première partie de la thèse. L'une concerne les points de correspondance entre autobus en région parisienne, l'autre s'intéresse sur la longue durée aux règles mises en oeuvre dans la conception des stations-service. Ces études démontrent en particulier que les procédés régulatoires, au-delà de leur variété (ils sont d'ordre organisationnel ou institutionnel ou de nature architecturale), reposent sur un principe commun de combinaisons d'éléments architecturaux structurants ou évolutifs.
Mejdoub, Mahmoud. "Indexation sémantique des images basée sur les réseaux réguliers de points". Nice, 2010. http://www.theses.fr/2010NICE4046.
Pełny tekst źródłaWith the growth of digital content volumes, the development of methods for index and searching this content becomes a necessity. In this thesis, we are focused on lattice vector quantization approach since its ability to provide an effective automatic structuring of visual feature vectors extracted from the images. The features extraction step is based on local descriptors obtained by the bag of words technique. Local areas selected in the image correspond to both salient points and homogeneous patches. The large number of local descriptors that can be obtained requires effective tools to organize them. For this, we propose a new indexing structure: the “embedded lattices tree” based on lattice vector quantization. The proposed approach is used both to accelerate the k nearest neighbours search and to improve the quality of semantic image classification
Belkebir, Mekki Kouider. "Conception de réseaux d'échangeurs de chaleur". Toulouse, INPT, 1989. http://www.theses.fr/1989INPT005G.
Pełny tekst źródłaLanier, Sandy. "Mise au point d’un mortier de piégeage à réseau poreux contrôlé". Thesis, Centrale Lille Institut, 2020. http://www.theses.fr/2020CLIL0027.
Pełny tekst źródłaThis PhD is part of the MACH3project funded by the French Investment Plan (PIA) -2nd phase. It contributes to the management of tritiated radioactive waste produced by the ITER fusion facility. The acceptance of this waste on a storage site requires a low rate of degassing of Tritium (radioactive isotope of H2). This research has developed cement mortars for conditioning tritiated nuclear waste,making it possible to limit the degassing of tritium by irreversible trapping of its gaseous forms. Composite mortars were formulated, based on conventional Portland cement, and integrating a hydrogen getter (Ag2O/MnO2), meeting the safety criteria of a radioactive waste storage facility and complying with the industrial specifications. After three months of maturation, their trapping performance, without preliminary drying, is between 75 and 95% (measured following a gamma irradiation test, generating H2in situ)
Sander, Agnès. "Les "points-de-réseaux" comme formes urbaines : morphogenèse et enjeux de conception". Paris 12, 1995. http://www.theses.fr/1995PA120026.
Pełny tekst źródłaThe planning of technical networks have more than widely ignored the "network-points", which have often been given a minor place with respect to moving elements (flow, circulation). Those points have nevertheless many different uses : they are functional ways of exit and entrance or connection, places that provide services, public areas and elements that articulate networks and territories. They are essential for the network to operate properly ; they are key elements of the territorial system as well. The network-points's design is submitted to many heterogeneous logics (each actor's rationale is different and doctrines often change). It is also dependant on the diversity of urban settings. Two empirical studies (following a more theoretical approach) brought out that in spite of the difficulties related to this situation, the resulting patterns can be guided and regulated. The first case study deals with bus connection in paris suburbs, the other one explores (from 1905 till now) the rules of gas stations's design and planning. Those case studies also revealed that the regulation (based upon institutional, organisational and architectural means) can be obtained by combining different types of architectural elements, so that some parts of the network-points are allowed to vary while the global shape is preserved
Pépin, Christine. "Quantification vectorielle et codage conjoint source-canal par les réseaux de points". Paris, ENST, 1997. http://www.theses.fr/1997ENST0030.
Pełny tekst źródłaDi, pietro Nicola. "Constellations finies et infinies de réseaux de points pour le canal AWGN". Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0006/document.
Pełny tekst źródłaThe probleme of transmission of information over the AWGN channel using lattices is addressed. Firstly, infinite constellations are considered. A nex family of integer lattices built by means of construction A with non-binary linear condes is introduced. These lattices are called LPA (Low-Density Construction A) and are characterised by sparse p-ary parity-chedk matrices, that put them in direct relation with LPDC codes. Two results about the Poltyrev-capacity-archieving qualities of this family are proved, respectively for logarithmic row degree and constant row degree of the associated parity-check matrices. The second result is based on some expansion poperties of the Tanner graphs related to these matrices. Another topic of this work concerns finite lattice constellations. A new proff that heneral random Construction A lattices achieve capacity under lattice deconding is provided, continuing and pimproving the work of Erez and Zamir (2004), Ordentlich an Erez (2012), and Ling and Belfiore (2013). This proof is based on Voronoi lattice constellations and MMSE scaling of the channel output. Finally, this approach is adapted to the LDA case abd ut us scgiwn tgat LDA lattices achive capacity with the ame transmission scheme, too. Once again, it is necessary to exploit the expansion properties of the Tanner graphs. At he end of the dissertation, an iterative message-passing algorithm suitable for decoding LDA lattices in high dimensions is presented
Pellegrin, Didier. "Algorithmique discrète et réseaux d'automates". Phd thesis, Grenoble 1, 1986. http://tel.archives-ouvertes.fr/tel-00321866.
Pełny tekst źródłaKharrat, Fatma. "Techniques adpatatives et classification des canaux a antennes multiples". Phd thesis, Télécom ParisTech, 2006. http://pastel.archives-ouvertes.fr/pastel-00002556.
Pełny tekst źródłaNannicini, Giacomo. "Le plus court chemin point-à-point sur des réseaux dynamiques qui dépendent du temps". Palaiseau, Ecole polytechnique, 2009. http://www.theses.fr/2009EPXX0016.
Pełny tekst źródłaPetitprez, Emmanuel. "Propriétés optiques et structurales de super-réseaux de boites quantiques auto-organisées de InAs". Toulouse, INSA, 2001. http://www.theses.fr/2001ISAT0006.
Pełny tekst źródłaIn this work we present a systematic study of the optical and structural properties of self-organized InAs quantum dot superlattices. The structures were grown by molecular beam epitaxy on (100) GaAs substrates with different spacing between the quantum dot layers. The samples have been investigated by transmission electron microscopy and photoluminescence. A quantitative analysis of microscopy images shows that spacer layer thickness reduction improves the quantum dots uniformity and vertical alignment. However, closely stacked quantum dot layers tend to relax through the formation of structural defects identified as microtwins We report for the first time on an unusual behavior of the photoluminescence peak position when the spacer layer thickness is reduced. This behavior is interpreted in terms of quantum dot size modification, electronic coupling, partial strain relaxation and non-radiative recombination through defect centers. Simulated photoluminescence spectra only fit the experimental data when these four features are considered. Additional experimental results also support our interpretation
Braune, Eric. "Réseau et management de l'innovation dans les secteurs de haute technologie : intérêt financier et organisationnel des réseaux dans les stratégies d'innovation des firmes industrielles de haute technologie". Thesis, Aix-Marseille 3, 2011. http://www.theses.fr/2011AIX32067.
Pełny tekst źródłaThrough an empirical study involving 172 high-tech industrial firms domiciled in the U.S. and embedded in networks of innovation financing by venture capital we show that the amount of expenditures in venture capital made by these firms impacts strongly and positively their Tobin's Q. In addition, our study illuminates the strategy of industrial firms embedded in networks of innovation financing. It appears that access to information concerning marketable innovations is highly constrained by relationships these firms have with financial venture capital companies. Thus, industrial firms building relationships with financial firms occupying a central place in the network get the most out of their nesting in it. These firms increase the amount of venture capital investments towards the same financial partners and this positively impacts their Tobin's Q. Therefore, our study reveals what an efficient relational capital is in financing networks of innovation
Landis, Stefan. "Réseaux de plots magnétiques sub-microniques réalisés à partir de substrats pré-gravés". Université Joseph Fourier (Grenoble), 2001. http://www.theses.fr/2001GRE10090.
Pełny tekst źródłaBarichard, Anne. "Enregistrement et analyses physico-chimiques de réseaux dans des matériaux composites polymères-points quantiques". Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28504/28504.pdf.
Pełny tekst źródłaDjellali, Assia. "Optimisation technico-économique d'un réseau d'énergie électrique dans un environnement dérégulé". Paris 11, 2003. http://www.theses.fr/2003PA112211.
Pełny tekst źródłaThe electric utility industry is undergoing a process of liberalization and deregulation. In this context new difficulties are occurring in the field of transmission network management and optimization. In addition to the classical difficulties encountered in a monopolistic context such as the nature of the network constraints, the considerable size of the problem to be solved and the nonlinearity of the network equations, the optimization procedure has to take into account the new constraints, which are related to the deregulation of the electrical energy market. The nature of this problem requires mathematical models, which allow us the optimization of a nonlinear criterion being subject to nonlinear constraints. In this thesis we investigate two different methods in order to determine on the one hand the difficulties related to the resolution of a nonlinear optimization problem and on the other hand the difficulties related to the network operation in a deregulated environment. The first method is the so-called Newton-Lagrange method, which is applied to a simplified 5-buses network in a monopolistic context in order to achieve a technico-economical optimization. The optimization goal is the determination of the optimal power generation of each power producer to ensure the security of the system operation and to minimize the system operation costs. Even though convergence time can be considerable due to the inequality constraints, the method provides satisfactory results and will be used as a basis in the second part. A second optimization tool is developed, which is based on the primal-dual interior point method. It is applied to a 12-buses test network in order to investigate and to resolve the difficulties related to a competitive environment such as congestion and energy lasses management, the control of generation deviations and the impact of the occurrence of new independent power producers in an established network. An important advantage of this method is the capacity to treat the inequality constraints in an easy way. The reliable and robust optimization tool provides very satisfactory results
Aracena, Julio. "Modèles mathématiques discrets associées à des systèmes biologiques : applications aux réseaux de régulation génétique". Université Joseph Fourier (Grenoble ; 1971-2015), 2001. http://www.theses.fr/2001GRE10215.
Pełny tekst źródłaAracena, Julio. "Modèles mathématiques discrets associées à des systèmes biologiques : applications aux réseaux de régulation génétique". Université Joseph Fourier (Grenoble), 2001. http://www.theses.fr/2001GRE1A004.
Pełny tekst źródłaFévrier, Clément. "Nouvelles phases électroniques avec orbitales eg dans les réseaux triangulaires". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY012/document.
Pełny tekst źródłaLayered compounds are materials which exhibit charge order and novel phase of matter. This is the case in layered transition metal compounds, which have their band conduction on d-orbitals, a key ingredient to understand their electronic properties. We will focus in this dissertation on systems where the crystal-field splits orbitals into two degenerate subsets, t2g and eg, and where conduction electrons are on eg-orbitals. It is the case for layered transition-metal dichalcogenides and 2H-AgNiO2, which are known to exhibit charge orders, a periodic arrangement of electrons on the lattice. Layered transition-metal dichalcogenides have various pattern, incommensurate or commensurate insulating charge orders, among them large-unit cells charge orders. 2H-AgNiO2 have a charge order but is yet metallic.In order to investigate their charge orders, we derive a generic multiorbital extended Hubbard model and we refine our interest to eg-orbital with strong local Coulomb interactions. With a tight binding approach and electrostatic considerations, then the unrestricted Hartree-Fock method, we build the phase diagrams as a function of the strength of the Coulomb interactions, local and short-range, and we tun the band structure using the ratio $t'/t$ of the $e_g$-orbitals. We unravel a rich phase diagram with more than ten phases where some transitions can be controlled by the band structure. In particular, we found pinball liquid phases, metallic threefold charge orders where localized charges (pins) are surrounded by itinerant charges (balls) on a honeycomb lattice. Phases with large unit-cells are also stabilized, such as incommensurate charge and orbital orders and a √12x√12 charge order. These electronic states are generic for the half-filled triangular lattice and are also found in the isotropic limit, which corresponds to the single-band spinful extended Hubbard model.To capture the properties of phases with strong band structure anisotropy in the Mott state, that unrestricted Hartree-Fock fails to capture, we derived a Heisenberg-like Hamiltonian from perturbation theory. Then, we build the phase diagram of this new effective Hamiltonian using a classical approach and exact diagonalization with a symmetry analysis and Lanczos algorithm for a 24-site cluster. Apart from the known phases of the Heisenberg model in presence of a field, the Y and V configuration, the 1/3 plateau, the ferro-orbital phase, the anisotropy of the band structure of eg-orbitals leads to other ordering with finite τy or τx and τz components, different stripe orders and orbital density waves. We build a rich phase diagram from this new Hamiltonian
Haddani, Mostafa. "Étude de modèles probabilistes de réseaux de télécommunication". Paris 6, 2001. http://www.theses.fr/2001PA066515.
Pełny tekst źródłaCosson, Marjorie. "Stabilité du réseau électrique de distribution. Analyse du point de vue automatique d'un système complexe". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC065/document.
Pełny tekst źródłaTo maintain the voltage within specified limits, local control laws of distributed generators (DGs) reactive power (Q) with respect to their voltage (U) have been considered. This work studies the impact of Q(U) control laws on distribution feeders’voltage stability. An empirical study confirms the risk of voltage instability and highlights its dependence on control law parameters. To help distribution grid operators to choose these parameters, three methods assessing stability are formulated.First, a formal method based on discrete abstraction and bisimulation calculation is developed. The proposed approach yields precise results but with a high computational load. Then, to overcome this issue, an analytical criterion adapting Q(U) control laws response time with respect to grid parameters is formulated. Finally, a general criterion, valid in any cases, is established in order to be included in the grid codes. To conclude this work, extension to more complex cases is discussed
Montalva, Medel Marco. "Problèmes type "Feedback Set" et comportement dynamique des réseaux de régulation". Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00629549.
Pełny tekst źródłaOsmane, Ali. "Réseaux spontanés et auto-organisants : du codage spatio-temporel au codage de réseaux". Phd thesis, Paris, Télécom ParisTech, 2011. https://pastel.hal.science/pastel-00686339.
Pełny tekst źródłaWe study the rotate-and-forward (RF) cooperative protocol in the two-hop MIMO relay networks. In these networks, the source communicates with the destination via a layer of relays. We consider different network configurations and we study the performance of the RF scheme using a new metric called outage gain. This gain gives us an exact characterization of the outage probability's behavior at moderate and high signal-to-noise ratio. Using this metric, we compare the performance of the RF scheme to the performance of other schemes having the same diversity order. Moreover, we assume that a feedback channel exists between the destination and the relays, and we use the channel knowledge to improve the performance of the RF scheme in terms of outage probability. We consider the physical layer network coding protocol; the compute-and-forward. We consider the transmission rate maximization problem and we relate it to the lattice shortest vector problem. We first implement this protocol for real Gaussian channels and one-dimensional lattices. We derive the maximum likelihood (ML) criterion and we propose a quasi-ML decoding technique and show that it can be implemented by using an Inhomogeneous Diophantine Approximation algorithm. Secondly, we generalize some of these results to the complex Gaussian multi-dimensional lattices, and introduce the flatness factor as a design criterion for lattice codes
Osmane, Ali. "Réseaux Spontanés et Auto-Organisants: du Codage Spatio-Temporel au Codage de Réseaux". Phd thesis, Télécom ParisTech, 2011. http://pastel.archives-ouvertes.fr/pastel-00686339.
Pełny tekst źródłaREBAI, Raja. "Optimisation de réseaux de télécommunications avec sécurisation". Phd thesis, Université Paris Dauphine - Paris IX, 2000. http://tel.archives-ouvertes.fr/tel-00010841.
Pełny tekst źródłaBoudjemaï, Farid. "Reconstruction de surfaces d'objets 3D à partir de nuages de points par réseaux de neurones 3D-SOM". Lille 1, 2006. https://ori-nuxeo.univ-lille1.fr/nuxeo/site/esupversions/bcedde4b-f138-4193-8cec-20a49de14358.
Pełny tekst źródłaRaouj, Abdallah. "Réseau de transport déréglementé un algorithme de point intérieur pour la résolution du sous-problème des opérateurs". Mémoire, Université de Sherbrooke, 2002. http://savoirs.usherbrooke.ca/handle/11143/4536.
Pełny tekst źródłaEl, Manouni Ahmed. "Réalisation d'un système ultra-vide et mise au point d'une technique de préparation de photocathodes à réseau de pointes de silicium. Premières mesures de courant d'émission de champ et de photoémission de champ". Clermont-Ferrand 2, 1990. http://www.theses.fr/1990CLF21299.
Pełny tekst źródłaTadjine, Athmane. "Structure électronique et propriétés de réseaux cohérents de nanocristaux semi-conducteurs". Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1I043/document.
Pełny tekst źródłaSemiconductor nanostructuration methods are a new route leading to the tuning of charge carriers behavior. This tuning is a direct consequence of the quantum confinement effect. In this thesis, we study using numerical and analytical approaches the properties of coherent superlattices of semiconductor nanocrystals. These superlattices are synthesized by bottom-up methods of oriented self-assembly. We show that their electronic band structures can be modeled by a simple effective Hamiltonian with analytical eigenvalues. In addition, we propose a top-down method where a periodic arrangement of holes is etched in semiconductor quantum wells using lithography. We show that it is possible to artificially reproduce two-dimensional lattices of high interest such as the honeycomb, the kagome and the Lieb lattices. Most of these lattices host Dirac fermions that we also recover in the superlattices. In another chapter, we study the effect of a static magnetic field on isolated nanocrystals and on honeycomb superlattices. We predict the presence of large magnetic moments in those systems. Finally, we show that, in PbSe square superlattices, a bond-sign disorder should arise. We find that this disorder is reducible by gauge transformations and we quantify the true (residual) disorder felt by electrons
Villain, Alban. "Etude et réalisation d'un système de points d'accès optimisés en technologie Bluetooth". Paris 6, 2004. http://www.theses.fr/2004PA066333.
Pełny tekst źródłaSertier, Anne-Sophie. "L'évolution modulaire des protéines : un point de vue phylogénétique". Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00842255.
Pełny tekst źródłaPerrigot, Rozenn. "Le choix des réseaux de points de vente : une approche par l'écologie des populations et les analyses de survie". Rennes 1, 2004. http://www.theses.fr/2004REN1G015.
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