Hydrodynamics of a flexible containment boom

Denne masteroppgaven studerer hydrodynamikken til en fleksibel inneslutningsbom. En global modell basert på teori om kabelstrukturer ble utviklet for å estimere deformasjonene til en bomstruktur som møter strøm. Denne globale modellen tar bare hensyn til det horisontale planet. Den bruker kontaktledningsligningen, luftmotstandskraften og stripeteorien for å finne formen strukturen bør ha. For å validere denne modellen ble det utført eksperimenter på en $5 m$ lang fleksibel bom med $30 cm$ dypgang. Strukturen ble slept med hastigheter som varierte mellom $0,08 m/s$ og $0,53 m/s$, noe som tilsvarer et Reynoldstall som varierte mellom $24000$ og $159000$. Bommen ble festet til vognen i begge ender, og det ble utført tester med ulike festebredder på $2,5 m$, $4 m$ og $5 m$. I tillegg ble det gjennomført en numerisk studie ved hjelp av CFD-beregningsprogrammet OpenFOAM. Simuleringene ble utført med det eksperimentelle oppsettet som inngangsverdier og inkluderte ulike representasjoner av bommens skjørt. En flat plate og tre ulike kurver som vender mot en strøm ($0,13 m/s$) med ulike helningsvinkler ble simulert. De numeriske resultatene viser at formen på den nedsenkede membranen har stor innvirkning på den påførte motstandskraften. Derfor må strukturens vertikale dimensjon tas i betraktning i den globale modellen. Ved å inkorporere varierende motstandskoeffisienter langs bommens lengde i den globale modellen, avhengig av kurven og helningsvinkelen, ble det vertikale aspektet til en viss grad tatt hensyn til. En sammenligning mellom denne modellen og den eksperimentelle studien viste at modellen var nøyaktig, men at den kunne trenge en viss utvikling og forbedring.This master's thesis studies the hydrodynamics of a flexible containment boom. A global model using cable structures theory was built to estimate the deformations of a boom structure facing a current. This global model only takes into account the horizontal plane. It uses the catenary equation, the drag force, and the strip theory to find the shape the structure should take. To validate this model, experiments were carried out on a $5 m$ long flexible boom model with a $30 cm$ draft. The structure was towed at velocities varying between $0.08 m/s$ and $0.53 m/s$ corresponding to a Reynolds number varying between $24000$ and $159000$. The boom was attached at both ends to the carriage and tests were carried out with different attachment widths of $2.5m$, $4m$, and $5m$. In addition, a numerical study was conducted, using the computational fluid dynamics (CFD) solver OpenFOAM. Simulations were performed using the experimental setup as input values and incorporated various representations of the boom's skirt. A flat plate and three different curves facing a current ($0.13 m/s$) with various inclination angles were simulated. The numerical results demonstrate that the shape of the submerged membrane significantly influences the applied drag force. Therefore, the vertical dimension of the structure must be considered within the global model. By incorporating varying drag coefficients along the length of the boom in the global model, dependent on the curve and inclination angle, the vertical aspect was taken into account to some extent. A comparison between this model and the experimental study proved that the model was accurate but could need some development and improvement

Traitement quantique de l’information pour les simulations quantiques

Quantum computing has gained momentum over the last two decades, thanks in particular to massive government and industry funding for quantum technologies. The quantum computer promises to solve problems that are currently untractable because of the unreasonable time it would take to solve them on the most powerful classical computers. The idea of the quantum computer is to use quantum properties of matter, such as entanglement and quantum superposition of states, to perform calculations in a new way. Quantum computing requires a new type of computer in which classical information bits, generally represented by the presence or absence of current at the input of a transistor, are replaced by quantum bits, also known as qubits, which are represented by the state of a quantum system. In addition, it is necessary to develop new algorithms that can be implemented on a quantum computer and that are able to benefit of the quantum advantage. This thesis focuses on these two complementary components: the construction of logic gates, a fundamental building block of any computer, and the design of algorithms for solving relevant problems on these machines. Among the most advanced platforms for quantum computing are superconducting circuits, which are the platform on which Google, IBM, Alice&Bob, Nord Quantique and many other companies have decided to bet on. Despite the advances of recent decades, many challenges remain to be overcome before existing machines are able to solve relevant problems and outperform classical computers. One of the challenges this thesis tackles is the realization of fast and high-fidelity two-qubit gates. Speed is crucial to be able to perform as many operations as possible before the qubits lose their quantum coherence, and high fidelity is required to minimize computational errors and enable quantum error correction to be implemented. In addition, some superconducting qubits are known to be affected by an undesirable interaction, the ZZ interaction, which, although relatively weak, affects the fidelity of quantum logic gates, making it challenging to achieve fidelities above 99.9% required for quantum error correction. Alongside the improvement of quantum computer components, it is important to develop applications for this new type of machine. Among the approaches explored, variational quantum algorithms (VQA) are the family of algorithms most likely to be applied on existing small-scale quantum computers. These are hybrid algorithms that require both classical and quantum computing resources. VQAs seem promising for solving many concrete problems of industrial interest, such as obtaining the properties of molecules or finding solutions to combinatorial optimization problems. Indeed, these problems can be formulated in terms of a Hamiltonian and solved by determining its ground state. To this end, VQAs use a parameterized quantum circuit called ansatz, whose parameters are optimized to approximate the ground state. A first challenge is to find an ansatz which, for a given problem, converges as efficiently as possible to the solution. A second challenge is to find a circuit made of logic gates that can be easily implemented on current physical platforms. The work carried out in this thesis tackles both of these challenges. In the first part of the thesis, we introduce a device we have designed that enables the implementation of parametric entanglement gates between two superconducting qubits. This approach has enabled our collaborators in Andrew Houck’s group at Princeton University to experimentally realize a√iSWAP operation in 15 ns with a fidelity of 98.8%, and this in a device where the ZZ interaction is suppressed. In the second part of the thesis, we developed an ansatz for VQAs to solve the Fermi Hubbard Model. This new ansatz uses the advantages of two pre-existing ansätze, and makes it possible to obtain the energy and ground state of the FHM with an accuracy several orders of magnitude better than standard ansätze, while significantly reducing the number of CNOT gates, which are generally imperfect and time-consuming to implement.La recherche en informatique quantique a pris de l’ampleur dans les deux dernières décennies, notamment grâce aux financements massifs des gouvernements et de l’industrie dans les technologies quantiques. L’ordinateur quantique promet de résoudre des problèmes qui jusqu’à présent restaient insurmontables à cause du temps déraisonnable qu’il faudrait pour les résoudre sur les ordinateurs classiques les plus puissants. L’idée de l’ordinateur quantique consiste à utiliser des propriétés quantiques de la matière, telles que l’intrication et la superposition quantique des états, pour effectuer des calculs d’une nouvelle manière. L’informatique quantique requiert un nouveau type d’ordinateur où les bits d’information classique, généralement représentés par la présence ou non de courant à l’entrée d’un transistor, sont remplacés par des bits quantiques aussi appelés qubits, et qui sont représentés par l’état d’un système quantique. De plus, il est nécessaire de développer de nouveaux algorithmes capables d’être implémentés sur un ordinateur quantique et capables de tirer parti de l’avantage quantique. Cette thèse porte sur ces deux composantes complémentaires : la construction de portes logiques, un bloc fondamental de tout ordinateur, et la création de meilleurs algorithmes pour résoudre des problèmes pertinents sur ces machines. Parmi les plateformes les plus avancées pour l’ordinateur quantique, on trouve les circuits supraconducteurs, qui sont la plateforme sur laquelle ont misé Google, IBM, Alice&Bob, Nord Quantique et bien d’autres compagnies. Malgré les avancées des dernières décennies, de nombreux défis restent à être relevés pour que les machines existantes soient en mesure de résoudre des problèmes pertinents et surpassent les ordinateurs classiques. L’un des défis auquel cette thèse s’attaque est la réalisation de portes logiques à deux qubits rapides et à haute fidélité. La rapidité est cruciale pour pouvoir réaliser le plus d’opérations possible avant que les qubits ne perdent leur cohérence quantique, et une haute fidélité est requise pour minimiser les erreurs de calcul et permettre d’implémenter de la correction d’erreurs quantiques. De plus, certains qubits supraconducteurs sont connus pour être affectés par une interaction indésirable, l’interaction ZZ qui, même si relativement faible, affecte la fidélité des portes logiques quantiques, empêchant d’atteindre des fidélités supérieures à 99.9% nécessaires à la correction d’erreurs. En parallèle avec l’amélioration des composantes de l’ordinateur quantique, il est important de développer des applications pour ce nouveau type de machine. Parmi les approches étudiées, les algorithmes quantiques variationnels (VQA) sont ceux qui sont les plus susceptibles d’être déployés sur les ordinateurs quantiques de petites tailles existants. Ce sont des algorithmes hybrides qui nécessitent à la fois de la puissance de calcul classique et quantique. Ces algorithmes semblent prometteurs pour résoudre de nombreux problèmes concrets d’intérêt industriel, comme obtenir les propriétés de molécules ou trouver les solutions de problèmes d’optimisation combinatoire. En effet, ces problèmes peuvent être formulés sous forme d’un Hamiltonien et résolus en déterminant son état fondamental. Dans ce but, les VQAs utilisent un circuit quantique paramétré appelé ansatz, dont les paramètres sont optimisés pour s’approcher de l’état fondamental. Un premier défi consiste à trouver un ansatz qui permette, pour un problème donné, de converger le plus efficacement possible vers la solution. Un deuxième défi est de trouver un circuit fait de portes logiques facilement implémentables sur les plateformes physiques actuelles. Les travaux effectués dans cette thèse apportent des contributions à ces deux défis. Dans la première partie de la thèse, nous introduisons le dispositif que nous avons conçu et qui permet de réaliser des portes d’intrication paramétrique entre deux qubits supraconducteurs. Cette approche a permis à nos collaborateurs du groupe d’Andrew Houck de l’Université de Princeton de réaliser expérimentalement une opération de type √iSWAP en 15 ns avec une fidélité de 98.8%, et ce dans un dispositif où l’interaction ZZ est supprimée. Dans la seconde partie de la thèse, nous avons développé un ansatz pour les VQAs permettant de résoudre le modèle de Fermi Hubbard. Ce nouvel ansatz utilise les avantages de deux ansätze préexistants, et permet d’obtenir l’énergie et l’état fondamental du FHM avec une précision de plusieurs ordres de grandeur supérieure aux ansätze standards, et ce en réduisant significativement le nombre de portes d’intrication CNOT qui sont généralement imparfaites et longues à implémenter

Management of service crops for the provision of ecosystem services in vineyards: A review

Service crops are crops grown with the aim of providing non-marketed ecosystem services, i.e. differing from food, fiber and fuel production. Vineyard soils face various agronomic issues such as poor organic carbon levels, erosion, fertility losses, and numerous studies have highlighted the ability of service crops to address these issues. In addition to their ability to increase soil organic matter and fertility, and reduce runoff and erosion processes, service crops provide a large variety of ecosystem services in vineyards such as weed control, pest and disease regulation, water supply, water purification, improvement of field trafficability and maintenance of soil biodiversity. However, associating service crops with grapevines may also generate disservices and impair grape production: competition for soil resources with the grapevine is often highlighted to reject such association. Consequently, vinegrowers have to find a balance between services and disservices, depending on local soil and climate conditions, on their objectives of grape production and on the nature and temporality of the ecosystem services they expect during the grapevine cycle. This study proposes a review of the services and disservices provided by service crops in vineyards, and a framework for their management. Vinegrowers’ production objectives and pedoclimatic constraints form the preliminary stage to consider before defining a strategy of service crop management. This strategy assembles management options such as the choice of species, its spatial distribution within the vineyard, the timing of its installation, maintenance and destruction. These management options, defined for both annual and long-term time scales, form action levers which may impact cropping system functioning. Finally, we underline the importance of implementing an adaptive strategy at the seasonal time scale. Such tactical management allows adapting the cropping system to observed climate and state of the biophysical system during the grapevine cycle, in order to provide targeted services and achieve satisfactory production objectives

Identification of two novel powdery mildew resistance loci, Ren6 and Ren7, from the wild Chinese grape species Vitis piasezkii

Descriptive statistics of the phenotypic scores within the base mapping population 11-373. Powdery mildew symptoms in the field were evaluated in two subsequent years. Greenhouse, in vitro experiments and the qPCR-based molecular assay were carried out with three to four biological replicates of each seedling plant in 2014. (DOCX 14ย�kb

Accurate methods for the analysis of strong-drive effects in parametric gates

The ability to perform fast, high-fidelity entangling gates is an important requirement for a viable quantum processor. In practice, achieving fast gates often comes with the penalty of strong-drive effects that are not captured by the rotating-wave approximation. These effects can be analyzed in simulations of the gate protocol, but those are computationally costly and often hide the physics at play. Here, we show how to efficiently extract gate parameters by directly solving a Floquet eigenproblem using exact numerics and a perturbative analytical approach. As an example application of this toolkit, we study the space of parametric gates generated between two fixed-frequency transmon qubits connected by a parametrically driven coupler. Our analytical treatment, based on time-dependent Schrieffer-Wolff perturbation theory, yields closed-form expressions for gate frequencies and spurious interactions, and is valid for strong drives. From these calculations, we identify optimal regimes of operation for different types of gates including $i$SWAP, controlled-Z, and CNOT. These analytical results are supplemented by numerical Floquet computations from which we directly extract drive-dependent gate parameters. This approach has a considerable computational advantage over full simulations of time evolutions. More generally, our combined analytical and numerical strategy allows us to characterize two-qubit gates involving parametrically driven interactions, and can be applied to gate optimization and cross-talk mitigation such as the cancellation of unwanted ZZ interactions in multi-qubit architectures.Comment: 20 pages, 9 figures, 62 reference

Analyse génétique des variétés différentielles de blé utilisées dans la caractérisation des races de Puccinia striiformis agent de la rouille jaune

*INRA, Centre de Grignon-Versailles (FRA) Diffusion du document : INRA, Centre de Grignon-Versailles (FRA) Diplôme : Dr. d'Universit

Hybrid interface tracking method of multi-phase flows, for additive manufacturingand welding applications

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