Les plages de sable sont des écosystèmes dynamiques couvrant 70% des côtes mondiales. Ces systèmes abritent un cortège spécifique unique et assurent des fonctions essentielles de nourricerie, de nurserie et d’épuration des eaux. Or à proximité des côtes, la population humaine est en développement constant ce qui accroît les multiples pressions d’origine anthropique sur les écosystèmes côtiers. L’apport en excès de nutriments constitue une menace majeure qui peut se traduire par le développement d’importantes biomasses de macroalgues opportunistes (eutrophisation). La fréquence et l’intensité de ces blooms, communément formés de chlorophycées à court cycle de vie (ulves) et appelés marées vertes (MV), s'amplifient sur les côtes françaises et dans le Monde menaçant le fonctionnement de systèmes prépondérants et uniques.La plupart des études visant à déterminer les effets des MV sur la structure et le fonctionnement d’écosystèmes sédimentaires ont été conduites dans des environnements abrités, micro- ou atidaux. Cette problématique est restée presqu’inexplorée dans des écosystèmes plus dynamiques (systèmes ouverts et macrotidaux) en raison des difficultés de mise en place d’échantillonnage et de détection des effets de stress d’origine anthropique, inhérentes à la variabilité de ces systèmes. Cette thèse a donc eu pour objectif principal de combler ce manque et produire des connaissances en étudiant les réponses in situ des communautés benthiques de plages de sable fin macrotidales en présence ou non de MV. Quatre études ont été menées à différentes échelles spatio-temporelles et en considérant différents compartiments biologiques pour répondre à cette question générale.Ce travail de thèse montre qu’à l’échelle de la région Bretagne (variabilité intégrée sur 2700km de côtes et 7 ans) les communautés benthiques d’écosystèmes dynamiques sont modifiées significativement et de manière conservative par la présence de MV. Ce travail démontre aussi que les marées vertes impactent différemment la faune benthique en fonction du type d’habitat (plages semi-exposées vs. exposées), de la profondeur (mediolittoral vs. infralittoral), et du compartiment biologique (macrofaune benthique vs. juvéniles de poissons plats). Ces comparaisons ont permis d’identifier la faune benthique de médiolittoral inférieur des plages exposées comme étant le système le plus affecté par les MV. L’étude des variations à fine échelle spatio-temporelle de ce dernier montre que les caractéristiques faunistiques (uni- et multi-variées) sont modifiées le long d’un gradient de couverture d’algues vertes. Par exemple, la β-diversité décroît significativement le long de ce gradient. Afin d’explorer les processus pouvant expliquer ces modifications, et déterminer si ces changements ont des répercussions sur le fonctionnement de l’écosystème « plage de sable », les effets de l’accumulation d’ulves sur le réseau trophique à différent(e)s niveaux/échelles ont été mesurés. Les résultats de cette étude montrent qu’une importante biomasse d’ulves induit un changement de la structure entière du réseau trophique et une modification importante du fonctionnement trophique des plages. Les expérimentations menées au cours de cette thèse montrent que les changements observés sont induits par des effets directs (consommation de débris d’ulves) et indirects (modifications d’autres sources de nourriture) de la présence des MV.Cette thèse propose un cadre de travail visant à mieux détecter les effets de stress anthropiques sur la structure et le fonctionnement d’écosystèmes dynamiques. Dans un contexte de changement global forçant les écosystèmes à faire face à de multiples stress, cette approche pourrait se révéler particulièrement utile pour démêler, comprendre et prédire les effets de perturbations induites par les activités humaines sur le fonctionnement des écosystèmes et constituer une aide à la gestion de ces environnements particuliers. / Highly dynamic systems, often considered as resilient systems, are characterised by abiotic and biotic processes under continuous and strong changes in space and time. Because of this variability, the detection of overlapping anthropogenic stress is challenging. Coastal areas harbour dynamic ecosystems in the for of open sandy beaches, which cover the vast majority of the world’s ice-free coastline. These ecosystems are currently threatened by increasing human-induced pressure, among which mass-development of opportunistic macroalgae (mainly composed of Chlorophyta, so called green tides), resulting from the eutrophication of coastal waters. The ecological impact of opportunistic macroalgal blooms (green tides, and blooms formed by other opportunistic taxa), has long been evaluated within sheltered and non-tidal ecosystems. Little is known, however, on how more dynamic ecosystems, such as open macrotidal sandy beaches, respond to such stress. This thesis assesses the effects of anthropogenic stress on the structure and the functioning of highly dynamic ecosystems using sandy beaches impacted by green tides as a study case. The thesis is based on four field studies, which analyse natural sandy sediment benthic community dynamics over several temporal (from month to multi-year) and spatial (from local to regional) scales. In this thesis, I report long-lasting responses of sandy beach benthic invertebrate communities to green tides, across thousands of kilometres and over seven years; and highlight more pronounced responses of zoobenthos living in exposed sandy beaches compared to semi-exposed sands. Within exposed sandy sediments, and across a vertical scale (from inshore to nearshore sandy habitats), I also demonstrate that the effects of the presence of algal mats on intertidal benthic invertebrate communities is more pronounced than that on subtidal benthic invertebrate assemblages, but also than on flatfish communities. Focussing on small-scale variations in the most affected faunal group (i.e. benthic invertebrates living at low shore), this thesis reveals a decrease in overall beta-diversity along a eutrophication-gradient manifested in the form of green tides, as well as the increasing importance of biological variables in explaining ecological variability of sandy beach macrobenthic assemblages along the same gradient. To illustrate the processes associated with the structural shifts observed where green tides occurred, I investigated the effects of high biomasses of opportunistic macroalgae (Ulva spp.) on the trophic structure and functioning of sandy beaches. This work reveals a progressive simplification of sandy beach food web structure and a modification of energy pathways over time, through direct and indirect effects of Ulva mats on several trophic levels. Through this thesis I demonstrate that highly dynamic systems respond differently (e.g. shift in δ13C, not in δ15N) and more subtly (e.g. no mass-mortality in benthos was found) to anthropogenic stress compared to what has been previously shown within more sheltered and non-tidal systems. Obtaining these results would not have been possible without the approach used through this work; I thus present a framework coupling field investigations with analytical approaches to describe shifts in highly variable ecosystems under human-induced stress.

Abstract Multiple-input multiple-output transmitted signal design for the partially coherent Rayleigh fading channels with discrete inputs under a given average transmit power constraint is consider in this thesis. The objective is to design the space-time constellations and linear precoders to adapt to the degradation caused by the imperfect channel estimation at the receiver and the transmit-receive antenna correlation. The system is partially coherent so that the multiple-input multiple-output channel coefficients are estimated at the receiver and its error covariance matrix is fed back to the transmitter. Two constellation design criteria, one for the single and another for the multiple transmit antennae are proposed. An upper bound on the average bit error probability for the single transmit antenna and cutoff rate, i.e., a lower bound on the mutual information, for multiple transmit antennae are derived. Both criteria are functions of channel estimation error covariance matrix. The designed constellations are called as partially coherent constellation. Additionally, to use the resulting constellations together with forward error control codes requires efficient bit mapping schemes. Because these constellations lack geometrical symmetry in general, the Gray mapping is not always possible in the majority of the constellations obtained. Moreover, different mapping schemes may lead to highly different bit error rate performances. Thus, an efficient bit mapping algorithm called the modified binary switching algorithm is proposed. It minimizes an upper bound on the average bit error probability. It is shown through computer simulations that the designed partially coherent constellation and their optimized bit mapping algorithm together with turbo codes outperform the conventional constellations. Linear precoder design was also considered as a simpler, suboptimal alternative. The cutoff rate expression is again used as a criterion to design the linear precoder. A linear precoder is obtained by numerically maximizing the cutoff rate with respect to the precoder matrix with a given average transmit power constraint. Furthermore, the precoder matrix is decomposed using singular-value-decomposition into the input shaping, power loading, and beamforming matrices. The beamforming matrix is found to coincide with the eigenvectors of the transmit correlation matrix. The power loading and input shaping matrices are solved numerically using the difference of convex functions programming algorithm and optimization under the unitary constraint, respectively. Computer simulations show that the performance gains of the designed precoders are significant compared to the cutoff rate optimized partially coherent constellations without precoding. / Tiivistelmä Väitöskirjassa tarkastellaan lähetyssignaalien suunnittelua osittain koherenteissa Rayleigh-häipyvissä kanavissa toimiviin monitulo-monilähtöjärjestelmiin (MIMO). Lähettimen keskimääräinen lähetysteho oletetaan rajoitetuksi ja lähetyssignaali diskreetiksi. Tavoitteena on suunnitella tila-aikakonstellaatioita ja lineaarisia esikoodereita jotka mukautuvat epätäydellisen kanavaestimoinnin aiheuttamaan suorituskyvyn heikkenemiseen sekä lähetin- ja vastaanotinantennien väliseen korrelaatioon. Tarkasteltavien järjestelmien osittainen koherenttisuus tarkoittaa sitä, että MIMO-kanavan kanavakertoimet estimoidaan vastaanottimessa, josta niiden virhekovarianssimatriisi lähetetään lähettimelle. Työssä esitetään kaksi konstellaatiosuunnittelukriteeriä, toinen yhdelle lähetinantennille ja toinen moniantennilähettimelle. Molemmat kriteerit ovat kanavan estimaatiovirheen kovarianssimatriisin funktioita. Työssä johdetaan yläraja keskimääräiselle bittivirhetodennäköisyydelle yhden lähetinantennin tapauksessa sekä rajanopeus (cutoff rate), joka on alaraja keskinäisinformaatiolle, usean lähetinantennin tapauksessa. Konstellaatioiden käyttö yhdessä virheenkorjauskoodien kanssa edellyttää tehokaita menetelmiä, joilla bitit kuvataan konstellaatiopisteisiin. Koska tarvittavat konstellaatiot eivät ole tyypillisesti geometrisesti symmetrisiä, Gray-kuvaus ei ole yleensä mahdollinen.Lisäksi erilaiset kuvausmenetelmät voivat johtaa täysin erilaisiin bittivirhesuhteisiin. Tästä johtuen työssä esitetään uusi kuvausalgoritmi (modified bit switching algorithm), joka minimoi keskimääräisen bittivirhetodennäköisyyden ylärajan. Simulointitulokset osoittavat, että työssä kehitetyt konstellaatiot antavat paremman suorituskyvyn turbokoodatuissa järjestelmissä kuin perinteiset konstellaatiot. Työssä tarkastellaan myös lineaarista esikoodausta yksinkertaisena, alioptimaalisena vaihtoehtona uusille konstellaatioille. Esikoodauksen suunnittelussa käytetään samaa kriteeriä kuin konstellaatioiden kehityksessä eli rajanopeutta. Lineaarinen esikooderi löydetään numeerisesti maksimoimalla rajanopeus kun rajoitusehtona on lähetysteho. Esikoodausmatriisi hajotetaan singulaariarvohajotelmaa käyttäen esisuodatus, tehoallokaatio ja keilanmuodostusmatriiseiksi, jonka havaitaan vastaavan lähetyskorrelaatiomatriisin ominaisvektoreita. Tehoallokaatiomatriisi ratkaistaan numeerisesti käyttäen difference of convex functions -optimointia ja esisuodatusmatriisi optimoinnilla unitaarista rajoitusehtoa käyttäen. Simulaatiotulokset osoittavat uusien esikoodereiden tarjoavan merkittävän suorituskykyedun sellaisiin rajanopeusoptimoituihin osittain koherentteihin konstellaatioihin nähden, jotka eivät käytä esikoodausta.

Cette thèse propose d'explorer les textes que Henri Lefebvre (1901-1991) a consacré à un projet de connaissance des rythmes, une « rythmanalyse », terme qu'il emprunte à Gaston Bachelard, pour contribuer à ce que nous appelons une poétique urbaine. Henri Lefebvre a laissé une œuvre fondatrice dans les études urbaines contemporaines en théorisant l'avènement de la société urbaine moderne et en produisant une théorie critique de l'urbanisme et des espaces et des temps sociaux qui en résultent. Nous montrons que la théorie critique est solidaire d'une poétique issue du romantisme révolutionnaire de l'auteur, qu'il développe au contact de pratiques artistiques, notamment celles de l'Internationale Situationniste. À l'encontre de ce qu'il analyse comme le processus d'abstraction de l'espace et du temps urbain, la rythmanalyse fait partie de la quête d'un espace-temps approprié à même de métamorphoser la société urbaine et de restituer le corps total, afin que l'urbain devienne l’œuvre de l'homme. Lefebvre ne propose pas seulement une méthodologie qualitative d'observation des rythmes, mais une expérimentation rythmanalytique, dont nous pouvons imaginer la pratique sous la forme de l'utopie expérimentale. La rythmanalyse fournit ainsi les idées directrices d'une poétique appliquée, à même de créer des formes, des textures et des styles pour l'habiter urbain. Cette poétique urbaine, à la fois création et connaissance, procède par des pratiques expérimentales et restitue le jeu rythmique qui enrichit l'expérience esthétique de l'espace et du temps urbain. / This thesis proposes to explore the texts that Henri Lefebvre (1901-1991) devoted to his project of understanding rhythms, his « rhythmanalysis », a term borrowed from Gaston Bachelard, to contribute to what we call an urban poetics. Henri Lefebvre has produced fundamental work in contemporary urban studies in both his theorization of the advent of modern urban society, and his elaboration of a critical theory of urban planning with its resultant social spaces and temporalities. We show that this critical theory unfolds in line with his construction of a poetics, which is inspired by the revolutionary romanticism that the author developed through his contact with artistic practices, especially those of the Situationnist International. Against his analysis of abstraction as an inherent process of urban space and time, his rhythmanalysis contributes to the creation of an appropriate space-time, with its ability to transform urban society and reconfigure the Total body so that what is urban can be instead considered a work of art. Lefebvre provides not only a qualitative methodology for the observation of rhythms, but also the outline of a rhythmanalytic experimentation, which can be associated with the practices of an experimental utopia. Rhythmanalysis offers guidelines for an applied poetics; it goes as far as creating forms, textures and styles for urban living. This urban poetics, simultaneously a creative act and one steeped in knowledge, proceeds through experimentation and restores the rhythmic game that enriches our aesthetic experience of urban space and time.

Network coding has emerged as an attractive alternative to routing because of the through put improvement it provides by reducing the number of channel uses. In a wireless scenario, in addition, further improvement can be obtained through Physical layer Network Coding (PNC), a technique in which nodes are allowed to transmit simultaneously, instead of transmitting in orthogonal slots. In this thesis, the design and analysis of network coding schemes are considered, for wireless two-way relaying, multi-user Multiple Access Relay Channel (MARC) and wireline networks. In a wireless two-way relay channel with PNC, the simultaneous transmissions of user nodes result in Multiple Access Interference (MAI) at there lay node. The harmful effect of MAI is the presence of signal set dependent deep channel fade conditions, called singular fade states, under which the minimum distance of the effective constellation at the relay become zero. Adaptively changing the network coding map used at the relay according to channel conditions greatly reduces the impact of this MAI. In this work, we obtain these adaptive PNC maps, which are finite in number ,by completing partially filled Latin Squares and using graph vertex coloring. Having obtained the network coding maps, the set of all possible channel realizations is quantized into a finite number of regions, with a specific network coding map chosen in a particular region and such a quantization is obtained analytically for 2λ-PSK signal set. The performance of the adaptive PNC scheme for two-way relaying is analyzed and tight high SNR upper bounds are obtained for the average end-to-end symbol error probability, in terms of the average error probability of a point-to-point fading channel. The adaptive PNC scheme is generalized for two-way relaying with multiple antennas at the nodes. As an alternative to the adaptive PNC scheme for two-way relaying, a Distributed Space Time Coding (DSTC) scheme is proposed, which effectively re-moves the effect of singular fade states at the transmitting nodes itself without any Channel State Information at the Transmitter (CSIT), and without any need to change the PNC map as a function of channel fade conditions. It is shown that the singular fade states can be viewed equivalently as vector subspaces of C2, which are referred to as the singular fade subspaces. DSTC design criterion to minimize the number of singular fade subspaces and maximize the coding gain is formulated and explicit low decoding complexity DSTC designs are provided. For the K-user MARC, in which K source nodes want to transmit messages to a destination node D with the help of are lay node R, a new PNC scheme is proposed. Use of a many-to-one PNC map with conventional minimum squared Euclidean distance decoding at D, results in a loss of diversity order due to error propagation from the relay node. To counter this, we propose a novel low complexity decoder which offers the maximum diversity order of two. Next, we consider wire line networks and explore the connections between linear network coding, linear index coding and discrete polymatroids, which are the multi-set analogue of matroids. We define a discrete polymatroidal network and show that a fractional vector linear solution over a field Fq exists for a network if and only if the network is discrete polymatroidal with respect to a discrete polymatroid representable over Fq.An algorithm to construct networks starting from certain class of discrete polymatroids is provided. Every representation over Fq for the discrete polymatroid, results in a fractional vector linear solution over Fq for the constructed network. It is shown that a linear solution to an index coding problem exists if and only if there exists a representable discrete polymatroid satisfying certain conditions which are determined by the index coding problem considered. El Rouayheb et. al. showed that the problem of finding a multi-linear representation for a matroid can be reduced to finding a perfect linear index coding solution for an index coding problem obtained from that matroid. Multi-linear representation of a matroid can be viewed as a special case of representation of an appropriate discrete polymatroid. We generalize the result of El Rouayheb et. al. by showing that the problem of finding a representation for a discrete polymatroid can be reduced to finding a perfect linear index coding solution for an index coding problem obtained from that discrete polymatroid.

[pt] Processamento em arranjos de sensores é uma área com vasta aplicação, tanto civil quanto militar, por exemplo em sonar, radar, sismologia e comunicações sem fio. Por meio de processamento espacial e espácio-temporal é possível melhorar suas funcionalidades e explorar novas possibilidades. Esta área vem atraindo cada vez mais a atenção e os esfor¸cos da comunidade científica, especialmente agora, em que antenas phased-array se estabeleceram como uma tecnologia comercial e madura. Neste contexto, nós tratamos o problema de processamento com posto reduzido em processamento espacial (beamforming) e espácio-temporal de sinais radar e a nova área de radares com função dual de radar e comunicações (dualfunction radar-communications, DFRC), que pode ser resumida na incorporação de mensagens de comunicações nas transmissıes radar como uma tarefa secundária. Nesta tese, nós investigamos a aplicação de um novo esquema de reduções de posto baseado em interpolação e decimação em duas áreas distintas: processamento espacial e processamento espácio-temporal de sinais radar. Este algoritmo para redução de posto nunca havia sido testado nestes ambientes antes e apresentou resultados bastante expressivos. Nós também propomos simplificações para reduzir a complexidade computacional do algoritmo em bemforming. Quanto ao tópico de DFRC, nós propomos dois métodos originais para incorporar modulação de amplitude/fase aos lóbulos laterais do diagrama de irradiação do radar de forma robusta. Os métodos propostos são muito mais simples do que o estado-da-arte e apresentam desempenho superior em termos de robustez e aplicabilidade em operações de tempo-real. Nós ainda provemos várias outras análises, comparações e contribuições a esta nova área. / [en] Array processing is an area with many civilian and military applications, e.g. sonar, radar, seismology and wireless communications. By means of space and space-time processing it is possible to enhance their features and explore new possibilities. This area has been attracting increasingly more attention and gathering more efforts of the science community, especially now, that phased array antennas are established as a commercial and mature technology. Within this context, we address the problem of reduced rank processing in space and space-time radar signal processing and the new area of dual-function radar-communications (DFRC), which may be summarized as embedding communication messages into radar emissions as a secondary task for the radar. In this thesis, we investigate the application of a new joint interpolation and decimation rank reducing scheme in two different areas: beamforming and space-time radar processing. This rank reducing algorithm was never tested within these contexts before and shows impressive results. We also propose simplifications for decreasing the computational complexity of the algorithm in beamforming. In the topic of DFRC, we propose two original robust radar-embedded sidelobe phase/amplitude modulation methods which have simple closed form equations. The proposed methods are much simpler than the state of the art and have superior performance in terms of robustness and real-time applicability.

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<p>This dissertation is concerned with two of the largest questions that we can ask about the nature of physical reality: first, whether physical reality begin to exist and, second, what criteria would physical reality have to fulfill in order to have had a beginning? Philosophers of religion and theologians have previously addressed whether physical reality began to exist in the context of defending the Kal{\'a}m Cosmological Argument (KCA) for theism, that is, (P1) everything that begins to exist has a cause for its beginning to exist, (P2) physical reality began to exist, and, therefore, (C) physical reality has a cause for its beginning to exist. While the KCA has traditionally been used to argue for God's existence, the KCA does not mention God, has been rejected by historically significant Christian theologians such as Thomas Aquinas, and raises perennial philosophical questions -- about the nature and history of physical reality, the nature of time, the nature of causation, and so on -- that should be of interest to all philosophers and, perhaps, all humans. While I am not a religious person, I am interested in the questions raised by the KCA. In this dissertation, I articulate three necessary conditions that physical reality would need to fulfill in order to have had a beginning and argue that, given the current state of philosophical and scientific inquiry, we cannot determine whether physical reality began to exist.</p>

Projektet behandlar det sublima i relation till arkitektur; både som händelse, diskurs och institution. Genom ett event som dynamisk förskjuter arkitekturens parametrar och sätter dessa i kontinuerlig förändring i relation subjekt-tid och objekt-rum. Ett gränsöverskridande erfarande av arkitektur. / The project deals with the sublime in relation to architecture; both as event, discourse and institution. Through an event that dynamically shifts architectural parameters and position these in continuous change in relation to subject-time and object-space. A cross-border experience of architecture.

No description available.

Over recent years, the research and studies have focused on innovative solutions in various aspects and phases related to the high demands on data rate and energy for fifth-generation and beyond (B5G). This thesis aims to improve the energy efficiency, error rates, low-resolution ADCs/DACs, antenna array structures and sum-rate performances of a single cell downlink broadband millimetre-wave (mmWave) systems with orthogonal frequency division multiplexing (OFDM) modulation and deploying multi-user massive multiple inputs multiple outputs (MU mMIMO) by applying robust beamforming techniques and detection algorithms that support multiple streams per user (UE) in various environments and scenarios to achieve low complexity system design with reliable performance and significant improvement in users perceived quality of service (QoS). The performance of the four 5G candidate mmWave frequencies, 28 GHz, 39 GHz, 60 GHz, and 73 GHz, are investigated for indoor/outdoor propagation scenarios, including path loss models and multipath delay spread values. Results are compared to confirm that the received power and delay spread is decreased with increasing frequency. The results were also validated with the measurement findings for 60 GHz. Then several proposed design models of beamforming are studied and implemented modified algorithms of Hybrid Beamforming (HBF) approaches in indoor/outdoor scenarios over large scale fading wideband mmWave /Raleigh channels. Firstly, three beamforming based diagonalize the Equivalent Virtual Channel Matrix (EVCM) schemes with the optimal linear combining methods are presented to overcoming the self-interference problems in Quasi-Orthogonal-Space Time Block Code (QO-STBC) systems over narrowband mmWave Single-User mMIMO (SU mMIMO). The evaluated results show that the proposed beamforming based- Single Value Decomposition (SVD) outperforms the conventional beamforming and standard QO-STBC techniques in terms of BER and spectrum efficiency. Next, the proposed HBF algorithm approaches with the fully/ partially connected structures are developed and applied for sum-rate and symbol error rate (SER) performance maximization MU mMIMO-OFDM system, including HBF based on block diagonalization (BD) method Constraint/Unconstraint RF Power, Codebook, Kalman schemes. In addition, the modified near optimal linear HBF-Zero Forcing (HBF-ZF) and HBF-Minimum Mean Square Error (HBF MMSE) schemes, considering both fully-connected and partially-connected structures. Finally, Simulation results using MATLAB platform, demonstrate that the proposed HBF based codebook and most likely HBF based-unconstraint RF power algorithms achieve significant performance gains in terms SER and sum-rate efficiency as well as show high immunity against the deformities and disturbances in the system compared with other HBF algorithm schemes. / Ministry of Higher Education and Scientific Research, the Republic of Iraq