Global ETD Search

281	A Fractional Step Zonal Model and Unstructured Mesh Generation Frame-work for Simulating Cabin Flows Tarroc Gil, Sergi January 2021 (has links) The simulation of physical systems in the early stages of conceptual designs has shown to be a key factor for adequate decision making and avoiding big and expensive issues downstream in engineering projects. In the case of aircraft cabin design, taking into account the thermal comfort of the passengers as well as the proper air circulation and renovation can make this difference. However, current numerical fluid simulations (CFD) are too computationally expensive for integrating them in early design stages where extensive comparative studies have to be performed. Instead, Zonal Models (ZM) appear to be a fast-computation approach that can provide coarse simulations for aircraft cabin flows. In this thesis, a Zonal Model solver is developed as well as a geometry-definition and meshing framework, both in Matlab®, for performing coarse, flexible and computationally cheap flow simulations of user-defined cabin designs. On one hand, this solver consists of a Fractional Step approach for coarse unstructured bi-dimensional meshes. On the other, the cabin geometry can be introduced by hand for simple shapes, but also with Computational Aided Design tools (CAD) for more complex designs. Additionally, it can be chosen to generate the meshes from scratch or morph them from previously generated ones. / <p>The presentation was online</p> Zonal Model Thermal Comfort Fluid Simulation Aircraft Cabin Design NURBS Morphing Radial Basis Functions Meshing Co-located Mesh Unstructured Mesh Mesh Quality Mesh Smoothing Enlarged Orientation Theorem Fractional Step Method Boussinesq Adam Bashforth Helmholtz-Hodge Theorem Rhie and Chow Difference Schemes Gradient Evaluation Differential Heated Cavity Driven Cavity Draught Rate Aerospace Engineering Rymd- och flygteknik Fluid Mechanics and Acoustics Strömningsmekanik och akustik
282	Listening with the Unknown: Unforming the World with Slave Ears and the Musical Works Not-In-Between (2020) The Sound of Listening (2020) The Sound of Music (2022) Cox, Jessie January 2024 (has links) Advances in technologies of voice profiling shed new light on questions of listening and its entanglement with antiblackness as a structuring paradigm of modernity. To contest current conceptions of listening with regards to the question of race and antiblackness while also shining light on the potentials offered by blackness, this dissertation engages listening at three distinct sites that are entangled with this modern question of voice profiling AI. In the process, this dissertation elaborates on the ethical stakes involved in listening itself. Chapter 1 excavates the way in which the ears of enslaved Black lives were ritualized. It centers an analysis of the role of the punishment of ear cropping and how this performed both a claim over slaves’ belonging and an inhibition on their freedom. Scholarship from Hebrew law aids in uncovering the meaning of the specific form of punishment. The chapter concludes by comparing the conception of slaves’ ears to Black artistic expressions such as Harriet Jacobs’s various methods of narration in Incidents of a Slave Girl and Blind Tom Wiggins’ unique use of clusters and graphic notation in Battle of Manassas, so as to demonstrate their methods of resistance and refusal to a claimed all-encompassing regime of listening. Chapter 2 engages modern notions of sound and listening. The way in which sound is theorized and engaged in modern digital technologies is entangled with the conception of what listening is and what it entails. Hermann von Helmholtz provides an axis after which sound and listening, as well as the relation between an inner world of perceptions and an outer world of sensations, has to be engaged as a question of listening as entangled in societal questions. The chapter critically elaborates alongside questions of categorical distinction in sound, such as the use of skull shapes as referents for AI listening, instrument classification systems, and the general question of the form of sound, or sound as object. The concluding Chapter 3 discusses, alongside Sylvia Wynter’s work and Roscoe Mitchell’s piece S II Examples (date) the kinds of questions we must pose in the development of modern AI listening technologies to move past antiblackness. Immanuel Kant’s theorizing of race and his influence on Johann Friedrich Blumenbach’s classification of skulls relate tomodern voice profiling AI technology directly through the question of using cranial shapes. Wynter’s work challenges both a turn to varieties that do not allow the addressing of structural antiblackness, and a continuation of claims to proper knowledge on the basis of antiblackness. Ultimately, Wynter aids us in hearing Mitchell’s continual shapeshifting practice on the saxophone as a proposal towards a refiguring of our conception of sound, listening, and us. Music Music and race Racism and the arts Racism against Black people Slaves--Social conditions Listening--Study and teaching Listening (Philosophy) Artificial intelligence Automatic speech recognition African Americans--Music Helmholtz, Hermann von, 1821-1894 Blind Tom, 1849-1908 Wynter, Sylvia Mitchell, Roscoe, 1940-
283	Partikelmodellierung der Strukturbildung akustischer Kavitationsblasen in Wechselwirkung mit dem Schalldruckfeld / Particle modeling of acoustic cavitation bubble structure formation and interaction with the acoustic pressure field Koch, Philipp 29 August 2006 (has links) No description available. 530 Physik Mathematics and Computer Science akustische Kavitation Strukturbildung akustische Lichtenbergfigur nichtlineare radiale Blasendynamik Keller-Miksis-Modell Oberflächenstabilität Gasdiffusion Partikelmodellierung primäre und sekundäre Bjerkneskraft Reibungskraft virtuelle Masse Ultraschallfeld Helmholtz-Gleichung stehende Schallfeldmode Resonanzverschiebung Blasen-Flüssigkeits-Gemisch van Wijngaarden-Wellengleichung Einzelblase Vielblasensysteme Hochgeschwindigkeitsaufnahme acoustic cavitation structure formation acoustic Lichtenberg figur nonlinear radial bubble oscillation Keller-Miksis model surface stability gas diffusion particel modeling primary and sekundary Bjerknes force drag force added mass ultrasonic field Helmholtz equation standing wave field resonance shift bubble liquid mixture van Wijngaarden wave equation single bubble multi bubble systems high-speed video observations 33.12 30.20 RHK 000: Ultraschall {Physik: Akustik} RHH 150: Schallausbreitung -reflexion in Flüssigkeiten {Physik: Akustik}
284	Coupled-Cluster in Real Space Kottmann, Jakob Siegfried 24 August 2018 (has links) In dieser Arbeit werden Algorithmen für die Berechnung elektronischer Korrelations- und Anregungsenergien mittels der Coupled-Cluster Methode auf adaptiven Gittern entwickelt und implementiert. Die jeweiligen Funktionen und Operatoren werden adaptiv durch Multiskalenanalyse dargestellt, was eine Basissatz unabängige Beschreibung mit kontrollierter numerischer Genauigkeit ermöglicht. Gleichungen für die Coupled-Cluster Methode werden in einem verallgemeinerten Rahmen, unabhängig von virtuellen Orbitalen und globalen Basissätzen, neu formuliert. Hierzu werden die amplitudengewichteten Anregungen in virtuelle Orbitale ersetzt durch Anregungen in n-Elektronenfunktionen, welche durch Gleichungen im n-Elektronen Ortsraum bestimmt sind. Die erhaltenen Gleichungen können, analog zur Basissatz abh¨angigen Form, mit leicht angepasster Interpretation diagrammatisch dargestellt werden. Aufgrund des singulären Coulomb Potentials werden die Arbeitsgleichungen mit einem explizit korrelierten Ansatz regularisiert. Coupled-Cluster singles mit genäherten doubles (CC2) und ähnliche Modelle werden, für geschlossenschalige Systeme und in regularisierter Form, in die MADNESS Bibliothek (eine allgemeine Bibliothek zur Darstellung von Funktionen und Operatoren mittels Multiskalenanalyse) implementiert. Mit der vorgestellten Methode können elektronische CC2 Paarkorrelationsenergien und Anregungsenergien mit bestimmter numerischer Genauigkeit unabhängig von globalen Basissätzen berechnet werden, was anhand von kleinen Molekülen verifiziert wird / In this work algorithms for the computation of electronic correlation and excitation energies with the Coupled-Cluster method on adaptive grids are developed and implemented. The corresponding functions and operators are adaptively represented with multiresolution analysis allowing a basis-set independent description with controlled numerical accuracy. Equations for the coupled-cluster model are reformulated in a generalized framework independent of virtual orbitals and global basis-sets. For this, the amplitude weighted excitations into virtuals are replaced by excitations into n-electron functions which are determined by projected equations in the n-electron position space. The resulting equations can be represented diagrammatically analogous to basis-set dependent approaches with slightly adjusted rules of interpretation. Due to the singular Coulomb potential, the working equations are regularized with an explicitly correlated ansatz. Coupled-cluster singles with approximate doubles (CC2) and similar models are implemented for closed-shell systems and in regularized form into the MADNESS library (a general library for the representation of functions and operators with multiresolution analysis). With the presented approach electronic CC2 pair-correlation energies and excitation energies can be computed with definite numerical accuracy and without dependence on global basis sets, which is verified on small molecules. multiskalenanalyse lineare antwortfunktion electronische anregungsenergien erste quantisierung multiadaptives coupled-cluster multiresolution analysis multiresolution quantum chemistry multiresolution coupled-cluster multiresolution linear response real-space coupled-cluster real-space quantum chemistry real-space linear response first quantization basis-set independent explicitly correlated linear response explicitly correlated coupled-cluster bound state helmholtz greens function numerical grid methods alpert wavelets excitation energies correlation energies coupled-cluster linear response electronic-structure VE 5657 ddc:540
285	Better imaging for landmine detection : an exploration of 3D full-wave inversion for ground-penetrating radar Watson, Francis Maurice January 2016 (has links) Humanitarian clearance of minefields is most often carried out by hand, conventionally using a a metal detector and a probe. Detection is a very slow process, as every piece of detected metal must treated as if it were a landmine and carefully probed and excavated, while many of them are not. The process can be safely sped up by use of Ground-Penetrating Radar (GPR) to image the subsurface, to verify metal detection results and safely ignore any objects which could not possibly be a landmine. In this thesis, we explore the possibility of using Full Wave Inversion (FWI) to improve GPR imaging for landmine detection. Posing the imaging task as FWI means solving the large-scale, non-linear and ill-posed optimisation problem of determining the physical parameters of the subsurface (such as electrical permittivity) which would best reproduce the data. This thesis begins by giving an overview of all the mathematical and implementational aspects of FWI, so as to provide an informative text for both mathematicians (perhaps already familiar with other inverse problems) wanting to contribute to the mine detection problem, as well as a wider engineering audience (perhaps already working on GPR or mine detection) interested in the mathematical study of inverse problems and FWI.We present the first numerical 3D FWI results for GPR, and consider only surface measurements from small-scale arrays as these are suitable for our application. The FWI problem requires an accurate forward model to simulate GPR data, for which we use a hybrid finite-element boundary-integral solver utilising first order curl-conforming N\'d\'{e}lec (edge) elements. We present a novel `line search' type algorithm which prioritises inversion of some target parameters in a region of interest (ROI), with the update outside of the area defined implicitly as a function of the target parameters. This is particularly applicable to the mine detection problem, in which we wish to know more about some detected metallic objects, but are not interested in the surrounding medium. We may need to resolve the surrounding area though, in order to account for the target being obscured and multiple scattering in a highly cluttered subsurface. We focus particularly on spatial sensitivity of the inverse problem, using both a singular value decomposition to analyse the Jacobian matrix, as well as an asymptotic expansion involving polarization tensors describing the perturbation of electric field due to small objects. The latter allows us to extend the current theory of sensitivity in for acoustic FWI, based on the Born approximation, to better understand how polarization plays a role in the 3D electromagnetic inverse problem. Based on this asymptotic approximation, we derive a novel approximation to the diagonals of the Hessian matrix which can be used to pre-condition the GPR FWI problem. 621.384

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